Morco Instantaneous Water Heater

[alan_fincher]

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.

Hi Les,

 

Thanks for generous offer, but we are just about managing to generate enough warm water to wash hair, etc. I even risked a rather cool shower earlier.

 

As it only seems to be about 5 degrees outside, I'm guessing the water in our integral tank isn't a lot hotter. I think the real issue may be that the Morco just isn't powerful enough to heat the water significantly when it's starting from such a low base in the first place.

 

Other years I think we have had the water system part drained by now, so we really have no experience of trying to survive with a "summer" boat in a more wintry climate!

 

Alan (& Cath)

[paulcatchpole]

As it only seems to be about 5 degrees outside, I'm guessing the water in our integral tank isn't a lot hotter. I think the real issue may be that the Morco just isn't powerful enough to heat the water significantly when it's starting from such a low base in the first place.

 

Our Morco is doing okay at the moment, despite the water temp on the outside - I had Kate shouting from the shower the other day to turn it down a bit, and Kate being a hard northern girl can take it far hotter than me!

 

Our biggest problem with it is water flow and the 'trigger point' of the Morco for full burner power - we've just replaced our water pump as the old one was dying slowly and had got to the point where the shower on full didn't cause the Morco to fully spin up. The new one is better, but I'm suspecting the sediment cartridge on our two-stage water filter is getting blocked and not helping. Need to change it at the weekend, but I can't complain for £2.99 I guess.

 

So perhaps you will need to investigate the main gas/water valve with the diaphragm.

 

The thermocouple / flue temp sensor assembly wasn't very expensive from Morco themselves - they sell direct from their website at prices that are quite a bit cheaper than most chandlers seem to list.

 

Hope you get it sorted!

 

HTH, PC

 

PS: I can confess though, to amuse you, that we bought a new spark ignitor for it, after changing the battery in the old one and getting no response. Only afterwards did I spot I'd put the new battery in upside down. So if you need a new ignitor at any point, let us know as we've got a good one going spare here! :-)

[alan_fincher]

PS: I can confess though, to amuse you, that we bought a new spark ignitor for it, after changing the battery in the old one and getting no response. Only afterwards did I spot I'd put the new battery in upside down. So if you need a new ignitor at any point, let us know as we've got a good one going spare here! :-)

Battery !?!

 

Yours has a battery !?!

 

I dream of having a battery, rather than that "lovely" piezo-electric 'clicky' igniter!

 

Ours is the DH51 model (no longer made), wheras I believe current ones are DH61.

 

I don't know how much they differ ?

 

Alan

[paulcatchpole]

Battery !?!

 

Yours has a battery !?!

 

I dream of having a battery, rather than that "lovely" piezo-electric 'clicky' igniter!

 

Ours is the DH51 model (no longer made), wheras I believe current ones are DH61.

 

I don't know how much they differ ?

 

Alan

 

lol. Ours is a D61E, E for 'having a battery' I believe...

 

I don't think there's a lot different in the general operation between them, looking at the spares related stuff a while ago on Morco's website... But I may be wrong, and perhaps sizes of stuff are different enough to make the output different?

 

http://www.morcoproducts.co.uk/compatability-1-30.html

 

Looking at the above, it seems the main burner if different (but not the burner bar, whatever that is...) , the gas assembly is the same, but the water valve block is different. No idea if that makes much difference or not...

 

Specs for ours list max output as 9.4kw and a min of 25deg and max of 50deg water temp rise above input [or pehaps ambient, not clear!]. So that should mean that even with a near 0 input, it should be able to produce 40degree 'nicely hot' water?

 

PC

Edited October 30, 2008 by paulcatchpole

[Lizzy J]

Battery !?!

 

Yours has a battery !?!

 

I dream of having a battery, rather than that "lovely" piezo-electric 'clicky' igniter!

 

Ours is the DH51 model (no longer made), wheras I believe current ones are DH61.

 

I don't know how much they differ ?

 

Alan

 

We have one with a 'piezo' thingy which I always have great difficulty in using.(It doesn't seem to work half the time) I suspect the model may be the same, it certainly isn't new.

 

We have boated in winter quite a bit and know the water in the tank is often very cold but have never had a problem with the Morco heating the water. It is however rather temperamental and often requires a shout from the shower to turn it up or down. It has a habit of lurching from hot to cold for no apparent reason.

 

Not that this post will help you but I do sympathise!

[bottle]

For those with the Piezo, as with any spark ignited gas, ensure that the two 'contacts' are clean and the gap is set correctly.

 

If the spark goes in the wrong direction, spark will always take the easiest route, then ignition will be difficult, if not impossible.

 

Some trial and error is involved.

[alan_fincher]

Hello again you already very helpful people!

 

I still need to work out what to do with my Morco.

 

We got it lighting again, whilst away, and also managed to get enough soot out of the fins in the heat exchanger that it's burning much bluer than it was, (although still with more orangy yellow tips to the flames than I'd expect).

 

However water is still coming through tepid rather than hot, and throttling back the rate of flow of the water is more likely to cause the burners to shut down, than the temperature to rise.

 

I'm convinced all jets and burner passageways are clear, so it seems not enough gas is getting through.

 

As previously reported...

 

Input pressure - burners not running - 14.8" WG

Input pressure - with burners running - drops to 14.0" WG, (despite1/2" supply pipe).

Pressure at burners - 13.6" WG

 

Do these pressures sound OK, or should I be worried that measured pressure at input drops when it starts, despite a 1/2" supply pipe.

 

Does anybody have any ideas as to where I go next. I haven't fully understood the diaphragm thing, for instance. Can anybody explain how the gas flow is actually controlled.

 

Or am I at the stage where an amateur has exhausted the easy things to check, and I now need to try and find a professional to take a look.

 

I'm actually thinking that as many of the spares don't seem to be interchangeable between my (DH51) and latest (DH61) model, it might be more sensible to pension this one off, and fit a whole new modern replacement.

 

I'm not sure if dimensions and plumbing connections are the same, but if they were I think replacement unit is only around £200. I'm guessing I would be up for at least half that if I try and get current one repaired ?

 

Alan

[Guest TerryL]

Hello again you already very helpful people!

 

I still need to work out what to do with my Morco.

 

We got it lighting again, whilst away, and also managed to get enough soot out of the fins in the heat exchanger that it's burning much bluer than it was, (although still with more orangy yellow tips to the flames than I'd expect).

 

However water is still coming through tepid rather than hot, and throttling back the rate of flow of the water is more likely to cause the burners to shut down, than the temperature to rise.

 

I'm convinced all jets and burner passageways are clear, so it seems not enough gas is getting through.

 

As previously reported...

 

Input pressure - burners not running - 14.8" WG

Input pressure - with burners running - drops to 14.0" WG, (despite1/2" supply pipe).

Pressure at burners - 13.6" WG

 

Do these pressures sound OK, or should I be worried that measured pressure at input drops when it starts, despite a 1/2" supply pipe.

 

Does anybody have any ideas as to where I go next. I haven't fully understood the diaphragm thing, for instance. Can anybody explain how the gas flow is actually controlled.

 

Or am I at the stage where an amateur has exhausted the easy things to check, and I now need to try and find a professional to take a look.

 

I'm actually thinking that as many of the spares don't seem to be interchangeable between my (DH51) and latest (DH61) model, it might be more sensible to pension this one off, and fit a whole new modern replacement.

 

I'm not sure if dimensions and plumbing connections are the same, but if they were I think replacement unit is only around £200. I'm guessing I would be up for at least half that if I try and get current one repaired ?

 

Alan

The heat exchanger can get blocked internally with limescale and that will definitely affect the heat output. Get some Fernox DS3 descaler mix as instructed and using a small funnel, pour the hot liquid in and watch the bubbles! If bad it will need doing more than once.

 

http://www.fernox.com/?cccpage=ds3⊂=8

 

The heat exchanger will also need to be absolutely clear externally for the combustion gasses to get through or it will affect the flame same as not enough air so any soot or scale must be cleaned out thoroughly.

 

The height of the flame will be a good indication of sufficient gas supply so if this is lower than normal then it could be a restricted supply but try cleaning as suggested first, it will improve the flow and heat transfer considerably even if not the real problem.

Edited November 3, 2008 by TerryL

[alan_fincher]

Terry,

 

Many thanks.

 

I'm fairly OK that I've got the finning on the heat exchanger pretty clear. What I don't know is whether the soot that was in there had happened mostly recently, because of poor burning, or was longer standing.

 

Whilst taking the point about internal furring up of the waterways, it seems unlikely to be the prime cause of current difficulties. It's still worth treating it though, I'm sure, although it's a "take it out again" job, as it would need to be upside down.

 

We used the boat about a month ago, and got piping hot showers - this time water is very much cooler.

 

I appreciate that for a given burn rate the heater increases the temperature by a set amount, so if the input water coming from the tank is colder, the "hot" out will not be as hot. However the difference is too dramatic to just be down to water in the tank being cooler than a month ago.

 

It seems like a rapid failure of something, rather than anything blocking or furring. I can't say how high the flames were before, or even really how "orange". It's installed in an awkward space, and with the cover on, you can't even really get a straight look in the pilot light hole.

 

I'm still interested in the "gas control / diaphragm" side of things. My hunch is the gas getting through is not being controlled properly, but beyond that I'm at the limit of what I know.

 

Alan

[Guest TerryL]

Terry,

 

Many thanks.

 

I'm fairly OK that I've got the finning on the heat exchanger pretty clear. What I don't know is whether the soot that was in there had happened mostly recently, because of poor burning, or was longer standing.

 

Whilst taking the point about internal furring up of the waterways, it seems unlikely to be the prime cause of current difficulties. It's still worth treating it though, I'm sure, although it's a "take it out again" job, as it would need to be upside down.

 

We used the boat about a month ago, and got piping hot showers - this time water is very much cooler.

 

I appreciate that for a given burn rate the heater increases the temperature by a set amount, so if the input water coming from the tank is colder, the "hot" out will not be as hot. However the difference is too dramatic to just be down to water in the tank being cooler than a month ago.

 

It seems like a rapid failure of something, rather than anything blocking or furring. I can't say how high the flames were before, or even really how "orange". It's installed in an awkward space, and with the cover on, you can't even really get a straight look in the pilot light hole.

 

I'm still interested in the "gas control / diaphragm" side of things. My hunch is the gas getting through is not being controlled properly, but beyond that I'm at the limit of what I know.

 

Alan

 

I have found my old gas service technology books so I need to do some reading, I'll be back!

[Guest TerryL]

Terry,

 

Many thanks.

 

I'm fairly OK that I've got the finning on the heat exchanger pretty clear. What I don't know is whether the soot that was in there had happened mostly recently, because of poor burning, or was longer standing.

 

Whilst taking the point about internal furring up of the waterways, it seems unlikely to be the prime cause of current difficulties. It's still worth treating it though, I'm sure, although it's a "take it out again" job, as it would need to be upside down.

 

We used the boat about a month ago, and got piping hot showers - this time water is very much cooler.

 

I appreciate that for a given burn rate the heater increases the temperature by a set amount, so if the input water coming from the tank is colder, the "hot" out will not be as hot. However the difference is too dramatic to just be down to water in the tank being cooler than a month ago.

 

It seems like a rapid failure of something, rather than anything blocking or furring. I can't say how high the flames were before, or even really how "orange". It's installed in an awkward space, and with the cover on, you can't even really get a straight look in the pilot light hole.

 

I'm still interested in the "gas control / diaphragm" side of things. My hunch is the gas getting through is not being controlled properly, but beyond that I'm at the limit of what I know.

 

Alan

If it is scaled up internally then the difference will be more pronounced with cooler water and of course sooting up will also affect it. The diaphram will only control the gas on and off according to the water flow so a reduced gas flow should have no effect on the flame. However, excessive gas flow or insufficient air or a blocked flue will cause a yellow sooty flame. Rusty or corroded burners will also alter the flame.

 

The burner control has a soft start so if that fails to open fully it can affect the burner output but again it will not cause a yellow flame. There may be an air control that has been disturbed but usually they are factory fixed. I would look closely at the air intake through to the burners.

 

I was hoping for a simple explanation in my books to relay to you but they assume a level of knowledge so there is very little reference to the correct flame. As I've already said the yellow flame is caused by lack of air or excess gas. This link to bunsen burners and reference to cold and hot flames will hopefully convince you!

 

http://en.wikipedia.org/wiki/Bunsen_burner

 

A thorough service will I'm sure sort out your problem.

[LEO]

Hi,

 

Bung it. A fit a new one or better still fit a calorifier heated by the engine.

 

Much easier and will you be able to test for gas leaks with a Mamometer after all these works?.

 

Albi.

[alan_fincher]

Hi,

 

Bung it. A fit a new one or better still fit a calorifier heated by the engine.

 

Much easier and will you be able to test for gas leaks with a Mamometer after all these works?.

 

Albi.

Hi Albi,

 

Whilst I'd like to get around to fitting a calorifier, I'd like this to be in addition to, rather than as a replacemrnt to the Morco.

 

A calorifier is a great source of "free" hot water when cruising, but bugger all use if holed up somewhere for a day or to, (I really can't abide running engines whilst moored, just to provide essential services).

 

There appears to not be great differences in design between my 13 year old Morco, and latest models on sale now, and I feel it should be fixable, provided parts are available. I don't like junking repairable equiment, just because it doesn't have the Manufacturer's latest model number on it.

 

I'm not quite sure how a manometer can help test for leaks, other than on the input side of it, when it's not actually running. I already have a bubble tester which most BSS examiners seem to prefer as a way of finding small leaks over the manometer method, but I'm confident that the bits I have dismantled will have gone back together leak free.

 

Alan

[alan_fincher]

If it is scaled up internally then the difference will be more pronounced with cooler water and of course sooting up will also affect it. The diaphram will only control the gas on and off according to the water flow so a reduced gas flow should have no effect on the flame. However, excessive gas flow or insufficient air or a blocked flue will cause a yellow sooty flame. Rusty or corroded burners will also alter the flame.

 

The burner control has a soft start so if that fails to open fully it can affect the burner output but again it will not cause a yellow flame. There may be an air control that has been disturbed but usually they are factory fixed. I would look closely at the air intake through to the burners.

 

I was hoping for a simple explanation in my books to relay to you but they assume a level of knowledge so there is very little reference to the correct flame. As I've already said the yellow flame is caused by lack of air or excess gas. This link to bunsen burners and reference to cold and hot flames will hopefully convince you!

 

http://en.wikipedia.org/wiki/Bunsen_burner

 

A thorough service will I'm sure sort out your problem.

 

Terry,

 

Thanks for your continued advice.

 

I do understand the Bunsen burner point - having thought it through, I realise any yellowness in the flames points to insufficient air, (or just possibly "too much gas").

 

However it is very hard studying the design to see how the burners can be being starved of air. Everything has come out, and is quite clear with no blockages. There is also no significant rusting of any part.

 

"Too much gas" would also seem hard to explain, but I suppose can not be ruled out.

 

I think the next thing is to take it out, bring it home, and carefully examine everything that can be dismantled or descaled.

 

It's not obvious to me what parts can be bought. It's a D51 model, and although visually similar to the current D61, unfortunately it appears many parts are not interchangeable between the two.

 

A new one is about £200, but I'm keeping that option only as a last resort!

 

Alan

[LEO]

Hi Alan,

 

Agreed, but the calorifier as fitted to my boat has connections to the Kabola and a 1kw immersion heater as well as the engine.

 

When I had a gas fridge (Electrolux ) I had problems with the flame, had it serviced by Centre Caravans (now renamed) at Tiddington nr Thame and they replaced a filter in the gas line which was limiting the gas supply.

 

I use the gas in orange coloured bottles and they said the filters took care of any impurities in the gas supplied in those bottles rather than the gas in the blue bottles which tends to be 'cleaner'. Fridge worked OK for years after that.

 

 

Albi

[n.b.Goldie]

Hi Alan,

 

Agreed, but the calorifier as fitted to my boat has connections to the Kabola and a 1kw immersion heater as well as the engine.

 

When I had a gas fridge (Electrolux ) I had problems with the flame, had it serviced by Centre Caravans (now renamed) at Tiddington nr Thame and they replaced a filter in the gas line which was limiting the gas supply.

 

I use the gas in orange coloured bottles and they said the filters took care of any impurities in the gas supplied in those bottles rather than the gas in the blue bottles which tends to be 'cleaner'. Fridge worked OK for years after that.

 

 

Albi

I think, if I remember correctly, that when I put a Morco in my old boat a couple of years ago there was a filter in the 'gas input' that you connect your supply line to. Might be worth a check.

[alan_fincher]

I think, if I remember correctly, that when I put a Morco in my old boat a couple of years ago there was a filter in the 'gas input' that you connect your supply line to. Might be worth a check.

OK thanks, although it seems we could be chasing too much gas getting through, rather than not enough.

 

Have just been and bought a large tub of Fernox DS3 descaler, so failing any other suggestion, I plan to take it out the whole thing, and dismantle and clean as much as possible.

 

If it works I should have enough descaler left over to service most of the other Morcos on the canals - why can you not buy such things in sensible quantities!

 

Alan

[Batavia]

When I had a gas fridge (Electrolux ) I had problems with the flame, had it serviced by Centre Caravans (now renamed) at Tiddington nr Thame and they replaced a filter in the gas line which was limiting the gas supply.

 

Albi

 

One point to note is that these filters can be very, very fine - the gauze in the one in my old Sibir fridge was mounted on the back of a small orifice plate and was more or less invisible to the naked eye - I would never have noticed it if someone else hadn't told me to look for it and even when partially blocked, the blockage was not apparent without the aid of a magnifying glass..

 

So look for the invisible....it may or may not be there ( rather like paranoia)

 

Chris

[Dave Hannigan]

Hi Alan,

 

Just some more thoughts for you.

 

The pressures that you have measured are around normal, a little low but not low enough to make a significant difference.

 

As you said the incoming water temp will have an effect but you should still be usable.

 

Unfortunately on LPG it is not easy to measure the amount of gas used without some very accurate weighing and a bit of maths, so is not easy to guage whether the burners are overgassed.

 

The air intake is set in manufacture so is unlikely to change and you have said is clear, likewise the injectors are brass and just passing gas are unlikely to alter radically in size

 

If the flames are blue at the base with a well defined shape and (usually) a roar type sound then orange tips of flames could well be dust from the atmosphere or from the heat ex itself if you have just been cleaning it. If all the airways and flueways are clear then were you to do a flue gas analysis the I would expect the co reading to be below 10ppm quite often 0. The orangy flame may be a red (or orange ) herring.

 

What is the flowrate of the water?? This can be quite easily measured, along with the temperature. According to Morco you get a 25degree rise at 5.4 litres per minute and 50 degrees at 2.7litres per minute, with the settings at max and min. If your flow rate is higher then you need to regulate to this and see what the rise is.

 

I think you need to find out the flow rate through the appliance when it first fires.

 

let me know the results

[alan_fincher]

Oh rats!

 

A bit hard to take those measurements now, as the heater is currently lying on it's back in our spare room.

 

What I do know is that in it's least "throttled back" setting, around 5.5 litres of water are going through in a minute, (so close to it's rated 5 litres per minute). Run like this the water is barely more than luke warm.

 

If I took the dial right round to the point where it is restricting the water most, then the flow falls to only 2.3 (ish) litres per minute. Like that the water is fairly hot, (possibly just too hot to shower under), but obviously there is not a lot of it.

 

It's certainly not raising the temperature by the quoted amounts....

 

For my model, (the DH51) these are....

 

at 5 litres per minute difference 25 degrees

 

at 2.5 litres per minute difference 50 degrees

 

Without measuring it, I can tell I'm nowhere close to that.

[smileypete]

It's certainly not raising the temperature by the quoted amounts....

 

Try a descale, probably needs one anyway.

 

Low efficiency = scaled heat exchanger.

 

Also I'd change the diaphragm too.

 

cheers,

Pete.

Edited November 5, 2008 by smileypete

[alan_fincher]

Try a descale, probably needs one anyway.

 

Low efficiency = scaled heat exchanger.

 

Also I'd change the diaphragm too.

 

cheers,

Pete.

Thanks Pete,

 

I do plan to try descaling, but to be honest if it was working perfectly a month ago, and not now, it's hard to see how it's got furred up in 4 weeks of not being used.

 

The diaphragm, despite presumably being as old as the heater (13 years) seems to be in remarkably good nick. It's flexible, unmarked and definitely not holed. I can't see a lot of point in replacing, unless there's something about them I don't understand. (Incidentally this is the part that people always say is susceptible to frost damage - as it's flexible, I'm struggling to see why ? )

 

What did interest me though is it pushes up on a large flat disk that is mounted on a metal pin that passes through the side of the housing to control a gas valve. That disk takes considerable pressure to move, being a very tight fit in the seal it passes through. I've no practical experience of these things, but am surprised just how much resistance there is in that sliding joint. But again it's very hard to see how it could have suddenly gone wrong since a month ago, so I suppose it's meant to be like it is.

 

Inspirations failing me, and I really don't want to take the gas control side of it to bits, without knowing I can replace any seals or gaskets I damage.

 

Anyway tomorrow I'll try descaling, and have another go at the burner & jets (which seem clean already) and the heat exchanger fins, (pretty good, but I could get even clearer).

 

Anybody know a reliable engineer in the Hertfordshire area, who's codes of practice will permit them to work on an open flued device ?

[wergie]

Thanks Pete,

 

I do plan to try descaling, but to be honest if it was working perfectly a month ago, and not now, it's hard to see how it's got furred up in 4 weeks of not being used.

 

The diaphragm, despite presumably being as old as the heater (13 years) seems to be in remarkably good nick. It's flexible, unmarked and definitely not holed. I can't see a lot of point in replacing, unless there's something about them I don't understand. (Incidentally this is the part that people always say is susceptible to frost damage - as it's flexible, I'm struggling to see why ? )

 

What did interest me though is it pushes up on a large flat disk that is mounted on a metal pin that passes through the side of the housing to control a gas valve. That disk takes considerable pressure to move, being a very tight fit in the seal it passes through. I've no practical experience of these things, but am surprised just how much resistance there is in that sliding joint. But again it's very hard to see how it could have suddenly gone wrong since a month ago, so I suppose it's meant to be like it is.

 

Inspirations failing me, and I really don't want to take the gas control side of it to bits, without knowing I can replace any seals or gaskets I damage.

 

Anyway tomorrow I'll try descaling, and have another go at the burner & jets (which seem clean already) and the heat exchanger fins, (pretty good, but I could get even clearer).

 

Anybody know a reliable engineer in the Hertfordshire area, who's codes of practice will permit them to work on an open flued device ?

[wergie]

Hi Alan,

For what it's worth it sounds to me like your diaphragm has stretched, so it looks ok, but because it has streched it will not lift the gas valve far enough to admit sufficient gas onto the burner bar. Also worth lubricating the push rod/spindle with a little silicon grease if it is sticking.

Please also note that in a domestic situation you would be in contravention of numerous gas regs, which are there for a very good reason, but , as you also know they don't to apply to privately owned boats. Now, it is your boat, and you can do as you see fit......... but please remember a little knowlege can be a dangerous thing !!!!

 

Steve (gas installer)

[alan_fincher]

Steve, thanks.

 

Yes I'm well aware that such matters are more controlled in a domestic environment.

 

I'm very wary of gas on boats, so if I got to the stage where I thought what I was doing was iffy in any way, I would stop.

 

If necessary I'll junk this appliance and replace with it's modern counterpart,

 

The problem I face is that as I understand it an LPG certified CORGI person would not be prepared to do that work with an open flued device. So at the end of the day, even if I want to pay somebody to do work, it may not be possible.

 

Thanks for the tip about silicone grease - obvious, I guess, but I didn't want to do anything to make it freer moving than it's intended to be.

 

It sounds like replacing that diaphragm may be sensible, even though the current one is visually OK, (I need to check I can get one for my obsoleted model).

 

However, I still think the nature of the failure points to something that has gone wrong suddenly, rather than going slowly wrong over time.

 

Alan