Morco Instantaneous Water Heater

[alan_fincher]

OK, I'll risk the ridicule from those who don't like LPG instantaneous water heaters.

 

But "we have a problem".

 

Our Morco has worked fine, including on a trip out a month ago. However on this trip, the "hot" water has been decidedly luke warm, and getting worse.

 

In desperation, (and in need of a shower!), I tried investigating today, but despite what the manual says, it doesn't seem possible to get the burner out without some major dismantling.

 

I could get near the burner nozzles to feel, and brush, and they seem neither corroded, nor blocked. However on reassembly, it's not burning clean at all, (flames are horribly orange), and the water is barely being heated.

 

Other things we have tried....

 

1) Ran off other cylinder, in case pressure was low in the one we were using.

2) Powered on all other appliances, (hob/grill/oven), which are before the Morco in the supply chain. All burning fine, and power not reduced by trying to run the Morco as well

 

So gas supply is fine, at leas as far as kitchen, but the Morco sits at the far end, and at lowest point, so it's conceivable that any liquid or gunge in the pipe has made it down to the Morco end.

 

We don't really fancy quite a few days with no running hot water, (no calorifier or back boiler), but will not run an LPG device that's not burning cleanly, (not thati's producing hot water anyway ).

 

We are out of ideas - other than it seem like too little gas" or "too much air" - does anybody else have some inspiration please ?

 

Alan & Cath.

[paulcatchpole]

No great ideas other than to add that the furthest we've taken ours apart is to remove the pilot jet, ignitor, thermocouple and flue gas detector.

 

I had a brief attempt to remove the main burner but it seemed to be blocked in by other stuff and, as you say, contrary to the manual didn't want to come out. There must be a trick to it.

 

Does altering the lower [temperature/flow] knob, affect the cleanness of burn?

 

PC

[alan_fincher]

Does altering the lower [temperature/flow] knob, affect the cleanness of burn?

 

PC

Hi Paul,

 

In a word "no!"

 

If it's strangled right down, then you at least get a bit of heat in the water, but it's still burning much too orange.

 

I can't see how you can actually remove the burner, which looks like it could be drawn out sideways, but on either side is blocked by the water pipes going up to the heater part above. I got it sliding an inch or two until it hit one of those pipes, but it can't come out sideways or forwards despite manual just saying "remove the burner"

 

Alan

[paulcatchpole]

I can't see how you can actually remove the burner, which looks like it could be drawn out sideways, but on either side is blocked by the water pipes going up to the heater part above. I got it sliding an inch or two until it hit one of those pipes, but it can't come out sideways or forwards despite manual just saying "remove the burner"

 

Hi Alan,

 

Yep, that's where I got to! A little sideways movement, but it wasn't coming out. I gave up! :-)

 

Mind you, if it *was* working and now isn't, it's hard to believe all the rows of jets have become blocked? Sounds like you're right in the first place that it's too much of one or not enough of t'other. I can't remember what ours looks like under the cover, but can you dismantle the main gas valve malarkey and give it a clean, without removing the main burner?

 

PC

[Guest TerryL]

OK, I'll risk the ridicule from those who don't like LPG instantaneous water heaters.

 

But "we have a problem".

 

Our Morco has worked fine, including on a trip out a month ago. However on this trip, the "hot" water has been decidedly luke warm, and getting worse.

 

In desperation, (and in need of a shower!), I tried investigating today, but despite what the manual says, it doesn't seem possible to get the burner out without some major dismantling.

 

I could get near the burner nozzles to feel, and brush, and they seem neither corroded, nor blocked. However on reassembly, it's not burning clean at all, (flames are horribly orange), and the water is barely being heated.

 

Other things we have tried....

 

1) Ran off other cylinder, in case pressure was low in the one we were using.

2) Powered on all other appliances, (hob/grill/oven), which are before the Morco in the supply chain. All burning fine, and power not reduced by trying to run the Morco as well

 

So gas supply is fine, at leas as far as kitchen, but the Morco sits at the far end, and at lowest point, so it's conceivable that any liquid or gunge in the pipe has made it down to the Morco end.

 

We don't really fancy quite a few days with no running hot water, (no calorifier or back boiler), but will not run an LPG device that's not burning cleanly, (not thati's producing hot water anyway ).

 

We are out of ideas - other than it seem like too little gas" or "too much air" - does anybody else have some inspiration please ?

 

Alan & Cath.

 

It's more likely to be an air blockage or less likely too much gas, is it balance flue?

[Dave Hannigan]

Hi, Alan

Do you have access to a manometer ?

If you do then measure the burner pressure, it should be 36mbar. If you have not got that make sure you have about that at the inlet side.

If you have full pressure at the inlet but not at the burner, then my money would be on the diaphragm not opening the gas valve fully due to a hole.

 

happy searching

 

Dave

[alan_fincher]

It's more likely to be an air blockage or less likely too much gas, is it balance flue?

No,

 

It's not room sealed. That's why 'm being cautious as the results of poor combustion are as likely to end up inside as outside.

[alan_fincher]

Hi, Alan

Do you have access to a manometer ?

If you do then measure the burner pressure, it should be 36mbar. If you have not got that make sure you have about that at the inlet side.

If you have full pressure at the inlet but not at the burner, then my money would be on the diaphragm not opening the gas valve fully due to a hole.

 

happy searching

 

Dave

Dave

 

I don't have a manometer as such, but I think I've seen some clear hose on board somewhere that might just about double as one.

 

I have a test point in the gas feed just before it goes into the heater, so should be able to measure pressure there.

 

Are you suggesting there is a further point inside that I can attach to, please ?

 

Your diaphragm suggestion, (I didn't know it had one! ), sounds highly plausible, as it would square very well with something working well 4 weeks ago, (no hole), but now having rapidly deteriorated (small hole getting bigger).

 

The heater is as old as the boat (13 years) so is that a likely time to failure, please ?

 

I clearly cannot sort it away from home, but I'm guessing it's not a DIY job even if back at base ? Correct ??

 

Sorry lots of questions, but your input has been most helpful.

 

Thanks,

 

Alan

[MtB]

We are out of ideas - other than it seem like too little gas" or "too much air" - does anybody else have some inspiration please ?

 

Alan & Cath.

 

 

Yellow/orange flames means too little air/too much gas for complete combustion, and this is the reason for the poor water heating performance.

 

Usual reason for this occurring spontaneously is spider infestation. Those tiny spiders nest in the burner ducts and prevent enough gas flow and air induction. I can't remember how to remove the burners despite having a Morco myself(!), but I'm certain it isn't difficult. Clean out the gas inlet ducts and you'll probably restore blue flames and proper performance.

 

Cheers, Mike

[Guest TerryL]

Yellow/orange flames means too little air/too much gas for complete combustion, and this is the reason for the poor water heating performance.

 

Usual reason for this occurring spontaneously is spider infestation. Those tiny spiders nest in the burner ducts and prevent enough gas flow and air induction. I can't remember how to remove the burners despite having a Morco myself(!), but I'm certain it isn't difficult. Clean out the gas inlet ducts and you'll probably restore blue flames and proper performance.

 

Cheers, Mike

 

If it's not spiders it'll be fluff and dust if it's not been cleaned regularly. Get a paintbrush to loosen it and vacuum if possible. Also check the flue outlet is clean and clear. It's unlikely to be the heat exchanger blocked but it's another place to clean if it's been running sooty.

[alan_fincher]

Thanks all.....

 

Very little fluff/dust/rust etc in any of the bits I can get at.

 

Flue is clear, and peering down the top the heat exchanger fins look pretty clear too.

 

This really is a "working fine" to "barely working at all" in very little time, so general build up of grot in just a few days or weeks seems unlikely.

 

The spider thing is possible, but as it seems to be burning orange across it's entire width, (many burners), unless they have nested in each part of it equally, I'm not that hopeful.

 

It really has suffered a fairly catastrophic failure quite quickly, which is why something becoming holed sounds possible. (Although I would love it to be something I could fix without spare parts!).

 

Oh, did I say it's inconveniently located on the side of a shower cubicle, facing the outside wall of the boat, but with nothing like enough space to get at it "front on" Whoever came up with it's placement, certainly never expected to get involved in servicing or repairing it.

 

Alan

[Guest TerryL]

Thanks all.....

 

Very little fluff/dust/rust etc in any of the bits I can get at.

 

Flue is clear, and peering down the top the heat exchanger fins look pretty clear too.

 

This really is a "working fine" to "barely working at all" in very little time, so general build up of grot in just a few days or weeks seems unlikely.

 

The spider thing is possible, but as it seems to be burning orange across it's entire width, (many burners), unless they have nested in each part of it equally, I'm not that hopeful.

 

It really has suffered a fairly catastrophic failure quite quickly, which is why something becoming holed sounds possible. (Although I would love it to be something I could fix without spare parts!).

 

Oh, did I say it's inconveniently located on the side of a shower cubicle, facing the outside wall of the boat, but with nothing like enough space to get at it "front on" Whoever came up with it's placement, certainly never expected to get involved in servicing or repairing it.

 

Alan

 

I don't know if this is your model http://www.morcoproducts.co.uk/resources/4...ual_English.pdf but it also mentions insects blocking the burners. The gas and air mixes in the bottom of the burner tube inlet so any blockage in the tube and the burner outlets will effect the flame. The other possibilty is a maladjustment of the gas or air but I could see no reference to this or any adjuster.

[Dave Hannigan]

Hi Alan

I have no direct experience with Morco so am working from a very bad diagram on the net.

 

There will normally be another test point somewhere around the burners, which with the appliance off will read 0, so reads the actual pressure available at the burners. If this is lower than it should be then you will not be generating the heat required and could also account for the different flame picture you are getting.

 

If the flames are fairly strong and blue at the base near the burners then orange tips could also be caused by dust from the atmosphere being drawn into the appliance. I'm assuming it is an open flue burner??

 

13 years for a diaphragm, wish they could get domestic combi's and multipoints to last that long, I'm onto the third in my combi in 9 years, first one lasted about 6 and went on christmas day, the second one lasted 2.

 

As I said I have no direct experience of Morco so am unable to advise on ease of change. You may be able to dismantle the water section from the rest of the heater, after that the diaphragm is usually straightforward.

 

Some pictures may be useful

 

Good luck

[RobinJ]

The spider thing is possible, but as it seems to be burning orange across it's entire width, (many burners), unless they have nested in each part of it equally, I'm not that hopeful.

Most of these types of heater don't have jets, the gas is controlled by a diaphpram valve and air is mixed with it as it passes to the burner. Any spider (or other insect) only has to crawl through the hole and spin (cocoon etc.) and the gas flow goes haywire affecting the whole burner!

How about a good vacuum cleaner with a small nozzle to prod in all the orifices? It that doesn't work then you will have to think about removing the whole unit so you can work on it!

[MtB]

Thanks all.....

 

Very little fluff/dust/rust etc in any of the bits I can get at.

 

Flue is clear, and peering down the top the heat exchanger fins look pretty clear too.

 

This really is a "working fine" to "barely working at all" in very little time, so general build up of grot in just a few days or weeks seems unlikely.

 

The spider thing is possible, but as it seems to be burning orange across it's entire width, (many burners), unless they have nested in each part of it equally, I'm not that hopeful.

 

It really has suffered a fairly catastrophic failure quite quickly, which is why something becoming holed sounds possible. (Although I would love it to be something I could fix without spare parts!).

Right, my brain was not fully engaged when I posted last night. It was late!

 

I should have mentioned in my previous post that incomplete combustion is also associated with blocked flue and/or sooted heat exchanger but you have now ruled this out, which is good progress. I also agree it is unlikely to be spiders nesting in the burner gas-ways because as you say, the chances of all eight (or so) gas ways becoming host at the same time is vanishingly small. I usually only see one gas-way, or possibly two, infested when I see it at all, leading to single rows of very obvious orange flames in amongst the blue.

 

HOWEVER, I should have warned you ***DO NOT USE IT UNTIL FIXED***. I'm sure you realise this, but this is a public forum. The yellow/orange flames will be producing carbon monoxide which may be spilling into the cabin atmosphere, which can lead to CO poisoning and death. Users of instantaneous water heater-powers showers are ESPECIALLY at risk.

 

 

Oh, did I say it's inconveniently located on the side of a shower cubicle, facing the outside wall of the boat, but with nothing like enough space to get at it "front on" Whoever came up with it's placement, certainly never expected to get involved in servicing or repairing it.

 

Alan

 

Why not just take it off the wall and bolt a new one on if it's urgent? They are still in production and not that expensive. Morco are in Hull. Google them for contact info. I often see them for sale in caravan places too. I saw one for sale in the chandlery at Harefield Marina the other day for example, in case you are anywhere near them.

 

But getting back to diagnosing the fault, the only cause left in the list of reasons for incomplete combustion is 'over-gassing'. The gas pressure to the burner is too high. This is caused by regulator failure, either in the Morco or on your gas bottle. Are the flames unusually large/powerful on the hob? Do you have a manometer you can attach to the burner pressure test point on the Morco to measure it?

 

Cheers, Mike

[alan_fincher]

Thanks to all....

 

What stars you all are.....

 

Some observations.....

 

1) Cylinder regulator was brand new this year, and believed good.

2) Hob/grill/oven are all working fine, no tinge of yellow, and are neither more or less powerful than usual.

3) Trying to run Morco does not reduce the gas available to other appliances, so any low pressure or blockage is after that point, if at all. (The Morco is several yards further on than anything else, and furthest from cylinder). All but the final bit of pipe with the stop cock and test point in is 1/2" pipe. The last foot or so is 3/8"

4) We are well aware of the dangers of incomplete combustion, and it's turned off, other than whilst investigating - all boat windows are open, and 2 CO monitors are in place.

5) I can probably cobble a crude manometer from plastic hose, The piece I have is probably just about long enough.

6) I've not gone looking for a test-point on the burner side, but can certainly establish the input pressure, I think, and whether it drops if you fire up the heater.

 

I'll report back.

 

Oh, and something on the flush system to the loo is now leaking everywhere too....

 

At least the stove is toasty warm!

 

Alan

[MtB]

Thanks to all....

 

What stars you all are.....

 

Some observations.....

 

1) Cylinder regulator was brand new this year, and believed good.

2) Hob/grill/oven are all working fine, no tinge of yellow, and are neither more or less powerful than usual.

3) Trying to run Morco does not reduce the gas available to other appliances, so any low pressure or blockage is after that point, if at all. (The Morco is several yards further on than anything else, and furthest from cylinder). All but the final bit of pipe with the stop cock and test point in is 1/2" pipe. The last foot or so is 3/8"

4) We are well aware of the dangers of incomplete combustion, and it's turned off, other than whilst investigating - all boat windows are open, and 2 CO monitors are in place.

5) I can probably cobble a crude manometer from plastic hose, The piece I have is probably just about long enough.

6) I've not gone looking for a test-point on the burner side, but can certainly establish the input pressure, I think, and whether it drops if you fire up the heater.

 

I'll report back.

 

Oh, and something on the flush system to the loo is now leaking everywhere too....

 

At least the stove is toasty warm!

 

Alan

 

Hi Alan,

 

The burner pressure is different from the inlet gas pressure. Low inlet gas pressure will not normally lead to excessive burner pressure (the fault we are currently trying to rule out). The inlet gas pressure is regulated down to a lower pressure (or range of pressures) which will be stated on the manufacturer's data plate on then appliance. There WILL be a test point somewhere for measuring this value (or range of values). Do you have the manufaturer's instructions book for the boiler to consult?

 

Whatever is wrong, we are looking for an unusual fault. We've ruled out the 'normal' reasons now. My Morco water heater is a modulating heater. Yours probably is too. That means the gas pressure to the burners (and consequently the flame size) is varied by a device in the water heater according to how fast the water it flowing through it and what setting you have on the flame size control knob and on the temp control knob. Does the flame size still vary on yours when you change the control settings? If yes, then the next step really IS to remove the burner assembly and inspect the insides of the gasways and air ports for blockages. I suggest cleaning the burner asembly out with an airline (once removed form the boiler) if no visual obstructions are apparent. Or put it through the dishwasher perhaps.

 

Whatever the mechanical fault turns out to be, remember that yellow flames are caused by insufficient combustion air mixed with the gas. Combustion is is entrained into the gas as it emerges into fresh air through the jets through the air ports/space just ahead of the jets. If the tubes in the burner that collect the mixed gas/air are resrtricted in any way the gas velocity is reduced resulting in less entrained air, richer mixture, and incomplete combustion.

 

Cheers, Mike

[AlanH]

Thanks to all....

 

What stars you all are.....

 

Some observations.....

 

1) Cylinder regulator was brand new this year, and believed good.

2) Hob/grill/oven are all working fine, no tinge of yellow, and are neither more or less powerful than usual.

3) Trying to run Morco does not reduce the gas available to other appliances, so any low pressure or blockage is after that point, if at all. (The Morco is several yards further on than anything else, and furthest from cylinder). All but the final bit of pipe with the stop cock and test point in is 1/2" pipe. The last foot or so is 3/8"

4) We are well aware of the dangers of incomplete combustion, and it's turned off, other than whilst investigating - all boat windows are open, and 2 CO monitors are in place.

5) I can probably cobble a crude manometer from plastic hose, The piece I have is probably just about long enough.

6) I've not gone looking for a test-point on the burner side, but can certainly establish the input pressure, I think, and whether it drops if you fire up the heater.

A friend had exactly the same problem and as others have mentioned spiders were the cause. We did get the burner out (thats where the spiders were) but we had to take the whole thing to my workshop and dismantle the it almost completely which took a long time and much swearing when we re-assembled it. Unfortunately this was about 5 years ago and I can't remember the details enough to give you disassembly instructions..

The spiders in this case had built a cocoon partially blocking the air intake to the burner thus causing a poor flame right across it.

Edited October 30, 2008 by AlanH

[johnthebridge]

Hello Alan-just a thought. Is this boat new to you this year? Have you used it in cold weather before? What type of gas are you using? It could be that the gas has become inert because of this cold spell. Just try and pick up a cylinder if possible, and give it a good shake. Or put it somewhere warm-ish for a while. Worth a try before getting too technical.

[alan_fincher]

It's not going well....

 

Firstly, we are on Propane, and definitely no problems with supply all other appliances are working as normal.

 

Checked the pressure at a test point just before the Morco. Measured expected 14.8" WG, although this does drop slightly as it fires up - more like 14.0" when running - I'd not have thought that enough to cause problems ?

 

Then found test point near burners, which measures something like 13.6" WG when fired up.

 

The instructions quote only that input should be 37 mbar for Propane, (i.e. 14.8" WG).

 

Eventually took the whole thing off wall, and partially dismantled. Burners seemed clean and unblocked, with airways clear, (there are 6 actually), and all 6 jets also fine.

 

However the fins in the heat exchanger were pretty sooted. Whether this is a build up over time, or a result of latest problems isn't obvious.

 

Put it all back together and reconnected, and..... IT WILL NOT BL**DY LIGHT!. I can get the pilot alight, but despite being well pointed at the FFD, as soon as you let the switch out again, the flame dies. I can't see I've damaged the FFD, or it's capillary, but it does also have tied into it stiff "wires" connected to a "combustion products discharge safety device" fitted to the top of the flue.

 

As I can't light it, even after training a gas lighter on the sensor for a minute or more, I suspect my amateur attempts to fix it are now over.

 

Bu**er!

 

Alan

[MoominPapa]

It's not going well....

 

Firstly, we are on Propane, and definitely no problems with supply all other appliances are working as normal.

 

Checked the pressure at a test point just before the Morco. Measured expected 14.8" WG, although this does drop slightly as it fires up - more like 14.0" when running - I'd not have thought that enough to cause problems ?

 

Then found test point near burners, which measures something like 13.6" WG when fired up.

 

The instructions quote only that input should be 37 mbar for Propane, (i.e. 14.8" WG).

 

Eventually took the whole thing off wall, and partially dismantled. Burners seemed clean and unblocked, with airways clear, (there are 6 actually), and all 6 jets also fine.

 

However the fins in the heat exchanger were pretty sooted. Whether this is a build up over time, or a result of latest problems isn't obvious.

 

Put it all back together and reconnected, and..... IT WILL NOT BL**DY LIGHT!. I can get the pilot alight, but despite being well pointed at the FFD, as soon as you let the switch out again, the flame dies. I can't see I've damaged the FFD, or it's capillary, but it does also have tied into it stiff "wires" connected to a "combustion products discharge safety device" fitted to the top of the flue.

 

As I can't light it, even after training a gas lighter on the sensor for a minute or more, I suspect my amateur attempts to fix it are now over.

 

Bu**er!

 

Alan

 

A bit more information that might help you: the "capilary" isn't, it's actually electrical. Basically co-axial cable with the outer in the form of a metal tube and the insulation made of ceramic. The FFD is a thermocouple which generates a small voltage which it just enough to keep an electromagnet in the valve energised.

 

The "combustion products safety device" is just an electrical thermostat which makes or breaks a connection when it gets too hot. I don't know which way around it's connected, it may be in series with the thermocouple and electromagnet and break the circuit on overheat, or it may be connected across the thermocouple and short it out on overheat. The former is probably more fail-safe, so I'd start by assuming that and try bridging the connections on the safety device. That may well get the pilot working again, but if not try disconnecting one wire and see if that works. Obviously, don't leave it in that state, you will have to replace the FFD/saftey assembly, but botching it temporarily might get the pilot going so you can work on the original problem.

 

It's possible that the root problem is gunk/corrosion in the control valve: that would explain both the problems you've seen.

 

MP.

[Guest TerryL]

A bit more information that might help you: the "capilary" isn't, it's actually electrical. Basically co-axial cable with the outer in the form of a metal tube and the insulation made of ceramic. The FFD is a thermocouple which generates a small voltage which it just enough to keep an electromagnet in the valve energised.

 

The "combustion products safety device" is just an electrical thermostat which makes or breaks a connection when it gets too hot. I don't know which way around it's connected, it may be in series with the thermocouple and electromagnet and break the circuit on overheat, or it may be connected across the thermocouple and short it out on overheat. The former is probably more fail-safe, so I'd start by assuming that and try bridging the connections on the safety device. That may well get the pilot working again, but if not try disconnecting one wire and see if that works. Obviously, don't leave it in that state, you will have to replace the FFD/saftey assembly, but botching it temporarily might get the pilot going so you can work on the original problem.

 

It's possible that the root problem is gunk/corrosion in the control valve: that would explain both the problems you've seen.

 

MP.

Fit a new thermocouple, they don't last forever and disturbing it probably finished it. A universal thermocouple may fit from heating suppliers or Wicks. Just a thought, did you check any gas filters or prove the flow, we had a problem with our caravan regulator sticking due to an oil in it recently, could also be any bit of muck.

[MoominPapa]

A universal thermocouple may fit from heating suppliers or Wicks.

A universal TC is probably no good in this case because the Morco one has the safety device hard-wired into it. This is a thermostat mounted on the collector-hood above the heat exchanger which I suspect is designed to shut everything down if the water supply fails but the gas supply keeps going.

 

Off topic, but there's an amusing account of what happens in this case without the safety here. (And make sure you're not drinking your tea/coffee before reading the "expanding foam" story, your keyboard will thank you!)

 

MP.

Edited October 30, 2008 by MoominPapa

[alan_fincher]

Well MP's description that all the failure devices are electrical, (despite looking otherwise), got me probing.

 

There appeared to be only about 0.002 ohms resistance across the who ensemble at the point it connects to what must control the gas cut off, (no idea if that's right or wrong ?).

 

I don't know what I did, because suddenly it worked again.

 

The heater will now fire up again, and the flames look a lot healthier than before, so taking it apart must have dislodged a suitable amount of crap.

 

However, the water is still only luke warm, and will only give a very cool shower.

 

We have never stayed on board when it is so cold outside, and I'm increasingly wondering if the water in our fresh water tank is so cold that the Morco just doesn't produce the heat fast enough to raise it through the required number of degrees. Obviously the water gets far hotter in summer, when it is coming out of the tank at well over 20 degrees, rather than now, when I guess the inlet temperature may well be below 10 degrees.

 

I've been putting off trying to find space for a calorifier. I think the time to provide an alternate hot water source may well be with us.

 

Thanks to all of you for the many useful suggestions received - I now know a lot more about Morco internals than I ever did before!

 

Alan

[Lesd]

Hi Alan, Cath,

Have just read your thread, sounds like a nightmare. If your stuck you're more than welcome to use of the shower on our boat. Its no problem just give me a an hours notice to heat up a tank full of hot water and bring some towls. Will be off early tomorrow so this evening would be the best bet, I'll be here until 9pm then I have to pop out to collect Heidi from the station.

Cheers

Les

PS Tried to PM you my mobile but your inbox is full !