Morco Instantaneous Water Heater

[Chris Pink]

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

 

At current labour rates you would probably save by buying a new unit, then getting the old one serviced in a workshop to sell it second hand.

[RobinJ]

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.

I thought that was the problem, there isn't a modern counterpart, the Morco is now the only one left?

 

Maybe they are not allowed to work on appliances that are not room sealed? Thereby we're in a catch 22 situation, can't replace it, can't repair it?

[MtB]

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.

 

I fully agree. If it worked ok a month ago and hasn't been used since then it won't be scale.

 

I am a boiler breakdown repair technician for a living and I fix the household version of these things from time to time. I also have a Morco D51 in my own boat.

 

I think yours has two separate problems.

 

1) Lack of servicing leads to poor pilot light 'flame picture'. Dust accumulates in the air ports of a pilot light causing a yellow sooty flame which slowly soots up an area of the HE leading to inadequate gas flow through it when the main burners light. This then leads to incomplete combustion of the main burners, massive soot production and a runaway effect. The thing rapidly degrades into a dangerous condition where 'spillage' of the flames occurs. (The Morco has a spillage sensor which will turn off the pilot flame if this happens.) I see this effect as a reason for the breakdown call two or three times a year in household appliances.

 

2) I've mentioned the second problem before but I don't think you've picked up on it. The Morco has a modulating burner. The control valve varies the flame size according to the water flow temperature being achieved. Cool outlet temp should result in maximum burner pressure/flame size. I think yours is not modulating and is stuck in the lowest burner pressure condition. Mine did this back in the summer resulting in cool showers. The reason turned out to be very simple and unrelated to the Morco itself, but I can't for the life of me remember what it was. Grrr... ...I'll post again when my memory re-boots.

 

Two more points. You keep commenting that you don't know if spares are available. They categorically ARE available! I know because I buy them myself from time to time directly from Morco in Hull, for both my own Morco and for my customers' Morcos. Second point is I (or any gas engineer) could come and fix it for you if you wish but the labour and parts cost will probably exceed the £200 price of a new one. Far better to replace it and keep the old one for spares/educational purposes for when the new one eventually breaks.

 

Lastly, there is a final reason for yellow flames that none of the professional gas bods here have pointed out so far (myself included!).... inadequate ventilation. Unlikely but if there is not a clear path to outside supplying fresh air getting into the room where the appliance is installed, yellow flame will result. Are your ventilators big enough and completely clear?

 

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

 

All engineers have to work to the same code of practice. It's Bs 5284-3:2005 LPG installations in boats – now replaced with ISO 10239:2000. I seem to remember it says open-flued appliances must not be installed in boats, in essence. This means an existing appliance may be repaired but not replaced with an identical one. This means the 'axe' principle needs to be applied. Change the handle first, then later the head. That way it remains the same axe....

 

Cheers, Mike

[Chris Pink]

1) Lack of servicing leads to poor pilot light 'flame picture'. Dust accumulates in the air ports of a pilot light causing a yellow sooty flame which slowly soots up an area of the HE leading to inadequate gas flow through it when the main burners light. This then leads to incomplete combustion of the main burners, massive soot production and a runaway effect. The thing rapidly degrades into a dangerous condition where 'spillage' of the flames occurs. (The Morco has a spillage sensor which will turn off the pilot flame if this happens.) I see this effect as a reason for the breakdown call two or three times a year in household appliances.

 

As someone who has a newly (ish) installed Morco, what servicing is needed to avoid this situation? Is there a Morco servicing guide anywhere, there is nothing in the manual that goes to this depth of detail.

[Guest TerryL]

I fully agree. If it worked ok a month ago and hasn't been used since then it won't be scale.

 

I am a boiler breakdown repair technician for a living and I fix the household version of these things from time to time. I also have a Morco D51 in my own boat.

 

I think yours has two separate problems.

 

1) Lack of servicing leads to poor pilot light 'flame picture'. Dust accumulates in the air ports of a pilot light causing a yellow sooty flame which slowly soots up an area of the HE leading to inadequate gas flow through it when the main burners light. This then leads to incomplete combustion of the main burners, massive soot production and a runaway effect. The thing rapidly degrades into a dangerous condition where 'spillage' of the flames occurs. (The Morco has a spillage sensor which will turn off the pilot flame if this happens.) I see this effect as a reason for the breakdown call two or three times a year in household appliances.

 

2) I've mentioned the second problem before but I don't think you've picked up on it. The Morco has a modulating burner. The control valve varies the flame size according to the water flow temperature being achieved. Cool outlet temp should result in maximum burner pressure/flame size. I think yours is not modulating and is stuck in the lowest burner pressure condition. Mine did this back in the summer resulting in cool showers. The reason turned out to be very simple and unrelated to the Morco itself, but I can't for the life of me remember what it was. Grrr... ...I'll post again when my memory re-boots.

 

Two more points. You keep commenting that you don't know if spares are available. They categorically ARE available! I know because I buy them myself from time to time directly from Morco in Hull, for both my own Morco and for my customers' Morcos. Second point is I (or any gas engineer) could come and fix it for you if you wish but the labour and parts cost will probably exceed the £200 price of a new one. Far better to replace it and keep the old one for spares/educational purposes for when the new one eventually breaks.

 

Lastly, there is a final reason for yellow flames that none of the professional gas bods here have pointed out so far (myself included!).... inadequate ventilation. Unlikely but if there is not a clear path to outside supplying fresh air getting into the room where the appliance is installed, yellow flame will result. Are your ventilators big enough and completely clear?

 

 

 

All engineers have to work to the same code of practice. It's Bs 5284-3:2005 LPG installations in boats – now replaced with ISO 10239:2000. I seem to remember it says open-flued appliances must not be installed in boats, in essence. This means an existing appliance may be repaired but not replaced with an identical one. This means the 'axe' principle needs to be applied. Change the handle first, then later the head. That way it remains the same axe....

 

Cheers, Mike

I agree with Mike, a sooty pilot could have started it all off and the flame height could be water temperature related which would point to a sticking valve but also it might be related to low water pressure preventing the valve from opening fully! Unfortunately when mentioning something I tend to assume everything will be checked fully as I would do it but that's not the case when done remotely, and obvious things like the pilot can get missed. I did think of ventilation and mentioned air but as this burner only runs intermittantly and is low power I considered it to be unlikely. Anyway that's my excuses and I'm sticking to them!

[MtB]

As someone who has a newly (ish) installed Morco, what servicing is needed to avoid this situation? Is there a Morco servicing guide anywhere, there is nothing in the manual that goes to this depth of detail.

 

To answer your exact question, the air ports on the pilot assembly need to be cleaned to remove dust/lint periodically. However often is necessary to prevent a yellow tip forming on the pilot flame. This can range from as often as every three months on a dusty boat with dogs or cats living on it too, to never. A holiday boat might need doing every four or five years perhaps. A live-aboard, probably annually.

 

There are a couple of pages on the details of boiler servicing on this website.... http://www.miketheboilerman.com/servicing.htm

 

 

Cheers, Mike

Edited November 6, 2008 by mike bryant

[smileypete]

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 ? )

 

Fair enough, another thing to check is that the water pressure from the pump is adequate.

 

 

Sometimes with things like this there are 2 or more gradually worsening marginal problems that appear suddenly as a single symptom, especially when there's a change in conditions.

 

So solution may need to be holistic, that is fix more than one problem alone.

 

cheers,

Pete.

Edited November 6, 2008 by smileypete

[alan_fincher]

Fair enough, another thing to check is that the water pressure from the pump is adequate.

Well the thing says it's rated to work at a maximum of 5 litres per minute, and I measured 5.5 litres per minute though it, so I think the water pump is still up to the job. Anyway even if flow rate were slow, it should just mean the less water gets relatively hotter, surely ?

 

Someone else has mentioned a stretched rather than visibly damaged diaphragm, so that might still be worth a try - they seem to cost around a tenner.

 

Thanks to all for continuing ideas, particularly the suggestion that replacement is unlikely to cost less than on site repair - much what I was thinking.

 

On that basis I can treat this one as expendable, and try a few more things, although for whatever reason I'm not confident I'll get it back to working properly.

 

Interesting about spares. I can find lots of parts being supplied for the current D61B, but very little for the D51B. There is a compatibility chart available, which shows relatively few of the D61B parts as usable in a D51B - well unless I'm reading it wrong!

 

Alan

[Guest TerryL]

Well the thing says it's rated to work at a maximum of 5 litres per minute, and I measured 5.5 litres per minute though it, so I think the water pump is still up to the job. Anyway even if flow rate were slow, it should just mean the less water gets relatively hotter, surely ?

 

Someone else has mentioned a stretched rather than visibly damaged diaphragm, so that might still be worth a try - they seem to cost around a tenner.

 

Alan

 

No harm in trying a diaphram but flow rate isn't pressure and if it's too low then it may not be able to lift the diaphram sufficiently to give full flame. What is the heater water pressure requirements and what does your pump cut in at?

[alan_fincher]

No harm in trying a diaphram but flow rate isn't pressure and if it's too low then it may not be able to lift the diaphram sufficiently to give full flame. What is the heater water pressure requirements and what does your pump cut in at?

The pump is a fairly standard ShurFlo one, and not that old. Although the previous one was a nominally 30 psi one, the evidence is that the one I have now is probably the 45 psi (3.1 bar) model that is quoted as cutting in at 25 psi (1.8 bar) +/- 5 psi (0.4 bar). (Not absolutely sure of that - I'd need to get a model number off the pump). A largish accumulator (5L) is fitted.

 

The documentation for the water heater helpfully gives no minimum feed pressure, only a maximum (10 bar). Seems a bit odd to me ?

 

Water pressure has not been a problem previously, and flow both through the Morco and at cold taps is as expected.

 

I've just been treating the coil with Fernox descaler. Based on their colour change indicator, very little scale has been removed. I've also thoroughly hosed through the finning, to get rid of any residual soot or other matter.

[Guest TerryL]

The pump is a fairly standard ShurFlo one, and not that old. Although the previous one was a nominally 30 psi one, the evidence is that the one I have now is probably the 45 psi (3.1 bar) model that is quoted as cutting in at 25 psi (1.8 bar) +/- 5 psi (0.4 bar). (Not absolutely sure of that - I'd need to get a model number off the pump). A largish accumulator (5L) is fitted.

 

The documentation for the water heater helpfully gives no minimum feed pressure, only a maximum (10 bar). Seems a bit odd to me ?

 

Water pressure has not been a problem previously, and flow both through the Morco and at cold taps is as expected.

 

I've just been treating the coil with Fernox descaler. Based on their colour change indicator, very little scale has been removed. I've also thoroughly hosed through the finning, to get rid of any residual soot or other matter.

That pressure should be enough but worth checking. You have to make sure the Fernox can get right through and out the otherside of the heat exchanger pipe to do it's job properly. When it stops fizzing after reheating it's nearly done. Someone else mentioned a sticking diaphram spindle and suggested lubricating it.

[alan_fincher]

I've now found in a different part of the paperwork, (not with the main data ) that it says minimum water pressure is 1 bar, and maximum 10 bar.

 

I'm confident the pump is cutting in way above 1 bar.

 

I did the descaling with it tipped upside down, feeding it into one connector, and catching it as it came out the other, letting it stand for a while, then pushing some more through, It's supposed to change colour if its converting anything. It did so only briefly at the beginning, after which it came out same colour as it went in.

 

I'd say it had a very light coating, but nothing more.

 

Having had the burners out again, they and the jets are quite clear, and there is no way in the world air flow is restricted. The heat exchanger fins are also 100% clear.

 

I'll refit it over the next few days, and if it's still crap, I think I'll replace it, as the fault would be in the gas related bits I do not wish to start meddling with. Or do I gamble a tenner on a diaphragm ?

[paulcatchpole]

Or do I gamble a tenner on a diaphragm ?

 

Go on, you know you want to - got to be worth a go!

 

PC

[smileypete]

I'll refit it over the next few days, and if it's still crap, I think I'll replace it, as the fault would be in the gas related bits I do not wish to start meddling with. Or do I gamble a tenner on a diaphragm ?

 

I'd put some silicone grease on the diaphragm spindle seal as mentioned.

 

Also I'd check if there's an inlet filter that may need unblocking.

 

If it still doesn't run right I'd try connecting a hose from a mains tap to the heater inlet, just to see if the extra pressure gets it working OK.

 

cheers,

Pete.

[alan_fincher]

I'd put some silicone grease on the diaphragm spindle seal as mentioned. Already done! Really the only change I've made at home, so the one small hope it may perform differently now.

Also I'd check if there's an inlet filter that may need unblocking. No nothing - the water plumbing goes straight into Hep2O, and the gas is a direct connection via a fitting with a manometer test point.

If it still doesn't run right I'd try connecting a hose from a mains tap to the heater inlet, just to see if the extra pressure gets it working OK. I think I get appreciably more pressure off my ShurFlo than the lame mains taps in the Marina. But as I said before, it's specced to work at 5 litres a minute on full flow, and I'm seeing 5.5 litres per minute. The problem is the faster the water goes through the less it's heated, of course, and at 5.5 litres a minute, it sure isn't getting hot.

 

Anyway, if I reinstall it, I'll recheck those flow rates, but also try and measure the temperature rise I'm getting, to see how far off design performance it really is.

 

That's if it doesn't p*ss water everywhere now I have had that side of things stripped down

[alan_fincher]

Well for anybody not bored with the subject by now, (and I sure am! .....)

 

I've reinstalled the cleaned up unit in the boat.

 

The good news is no gas or water leaks, following my dabblings, and the igniter still works, which it didn't the last time I took it out.....

 

It's burning pretty OK, although there is some orange to the tips of the flames.

 

I've measured temperature rise at the two flow rates that the manual quotes a figure for....

 

At 2.5 litres per minute I got 42.0 degree temperature rise, against 50 degrees specified.

At 5.0 litres per minute I got 21.3 degree temperature rise, against 25 degrees specified.

 

(These taken with a basic Maplin infra-red thermometer - not one of their more sophisticated ones, so may be subject to some error),

 

This means the actual temperature rises I'm getting are around 15% short of those specified by the manufacturer.

 

But I know there is a pressure drop when it's running, so that at input it's getting closer to 14.0" WG than 14.8" WG. This presumably will impact the maximum heat it can produce.

 

I'm now wondering with it at only 15% off the manufacturers spec, and given it's a 13 year old unit, apparently all original, whether what I'm seeing might not after all be pretty reasonable.

 

I wouldn't really want to shower under it on full flow, though!

 

Any further thought, please ?

 

Alan

[Guest TerryL]

Well for anybody not bored with the subject by now, (and I sure am! .....)

 

I've reinstalled the cleaned up unit in the boat.

 

The good news is no gas or water leaks, following my dabblings, and the igniter still works, which it didn't the last time I took it out.....

 

It's burning pretty OK, although there is some orange to the tips of the flames.

 

I've measured temperature rise at the two flow rates that the manual quotes a figure for....

 

At 2.5 litres per minute I got 42.0 degree temperature rise, against 50 degrees specified.

At 5.0 litres per minute I got 21.3 degree temperature rise, against 25 degrees specified.

 

(These taken with a basic Maplin infra-red thermometer - not one of their more sophisticated ones, so may be subject to some error),

 

This means the actual temperature rises I'm getting are around 15% short of those specified by the manufacturer.

 

But I know there is a pressure drop when it's running, so that at input it's getting closer to 14.0" WG than 14.8" WG. This presumably will impact the maximum heat it can produce.

 

I'm now wondering with it at only 15% off the manufacturers spec, and given it's a 13 year old unit, apparently all original, whether what I'm seeing might not after all be pretty reasonable.

 

I wouldn't really want to shower under it on full flow, though!

 

Any further thought, please ?

 

Alan

A modern 24KW gas combination boiler manages at least 9 litres per minute at 30 degree rise. Have you tried running it on acetalyne? Or a different regulator and have I mentioned descaling?

[alan_fincher]

A modern 24KW gas combination boiler manages at least 9 litres per minute at 30 degree rise. Have you tried running it on acetalyne? Or a different regulator and have I mentioned descaling?

Yes,

 

But this is a 13 year old instantaneous heater rated at 8.7KW, not a modern combi rated at 24 KW

 

It is only designed to give 25 degrees rise at 5 litres per minute, so unrealistic to expect more than that. If I could get that reliably it's more than adequate for our needs.

 

As already reported I have given it my best crack at descaling, but there really was no evidence that it had any significant amount of scale.

 

I'm not sure what the BSS attitude is to using acetylene, (or acetalyne if that's not the same thing), as an alternative to propane, but I think I'll pass on that one anyway, as most boatyards don't stock it, I think.

[Big COL]

Yes,

 

But this is a 13 year old instantaneous heater rated at 8.7KW, not a modern combi rated at 24 KW

 

It is only designed to give 25 degrees rise at 5 litres per minute, so unrealistic to expect more than that. If I could get that reliably it's more than adequate for our needs.

 

As already reported I have given it my best crack at descaling, but there really was no evidence that it had any significant amount of scale.

 

I'm not sure what the BSS attitude is to using acetylene, (or acetalyne if that's not the same thing), as an alternative to propane, but I think I'll pass on that one anyway, as most boatyards don't stock it, I think.

 

Hi Alan

 

Carbide lamps run on acetylene, modern things these didn't you know All you need is some calcium carbide, water and away you go used prior to the Davy lamp, the latest thing in narrowboats. A steel tube full of acetylene, lovely, thats the way to go.

Edited November 8, 2008 by Big COL

[Guest TerryL]

Yes,

 

But this is a 13 year old instantaneous heater rated at 8.7KW, not a modern combi rated at 24 KW

 

It is only designed to give 25 degrees rise at 5 litres per minute, so unrealistic to expect more than that. If I could get that reliably it's more than adequate for our needs.

 

As already reported I have given it my best crack at descaling, but there really was no evidence that it had any significant amount of scale.

 

I'm not sure what the BSS attitude is to using acetylene, (or acetalyne if that's not the same thing), as an alternative to propane, but I think I'll pass on that one anyway, as most boatyards don't stock it, I think.

I was only giving you an output comparison! And joking about the acetylene! And serious about the regulator. Did I mention descaling?

[Dave Hannigan]

Hi Alan,

from your figures it looks like 'thats as good as it gets'.

 

The only thing that will make any difference is getting 14.8" instead of 14". Is it possible to measure the pressure at the regulator?? If you can and you get 14.8" at the regulator, then the 0.8" loss is due to pipework. If this is the case you must ask if the work to improve the pressure loss is worth the effort for the gain you would get. Without doing the maths I would guess ony a degree or 2- not the full 8deg at 2.5l per min

[alan_fincher]

OK.

 

I fully appreciate a device that's virtually three times as powerful will heat the water, errm, nearly three times as fast.

 

That information doesn't really move me forward though.

 

I realise you are now joking about descaling, but on a more serious note, if it doesn't appear to have scaled up much in 13 years, it's hard to see that 4 weeks of total disuse could cause it.

 

If anything has so far produced an improvement, (and the jury is out on that), then it was a minuscule amount of silicone grease on the "spindle" attached to the pressure plate actuated by the diaphragm.

 

I also wonder if gas starvation is a small problem. Despite being fed by a (new) very adequately size regulator, and 1/2" pipe for all but the final few inches to the heater, I am measuring a drop in inlet pressure as it runs (14" WG instead of 14.8" WG). As the end of the feed pipe is the lowest part of the gas system, if any sludge had got in there, that is where it might gather. (I'm thinking of that black goo that sometimes gathers in LPG systems - although if undisturbed it doesn't usually make it out of the cylinders.....)

 

EDIT:

 

Sorry, also cross posted with Dave.

 

I can't easily measure pressure at the "cylinder" end of the boat - no manometer point there, as I tried to minimise joints.

 

The hob and oven sit half way along - I don't think either has a test point, but worth a look, I suppose. What I do know is that the flames on these don't visibly get smaller if the boiler is fired up.

 

However I haven't tried measuring the input pressure to the boiler with everything running. If that were less than 14" WG, it would further point to restricted flow. If I suspect anything it is the fact that the final bit of pipe before it rises to the heater is the low point. Any crap restricting that would not affect other appliances on board.

 

A lot of people seem to only use 3/8" pipe to a Morco, so I'm hoping our 1/2" feed is more than adequate.

[smileypete]

This means the actual temperature rises I'm getting are around 15% short of those specified by the manufacturer.

 

But I know there is a pressure drop when it's running, so that at input it's getting closer to 14.0" WG than 14.8" WG. This presumably will impact the maximum heat it can produce.

 

I'm now wondering with it at only 15% off the manufacturers spec, and given it's a 13 year old unit, apparently all original, whether what I'm seeing might not after all be pretty reasonable.

 

Any further thought, please ?

 

Not too bad, wonder what the pressure drop at the regulator is, ie is the drop occurring at the regulator or in the pipework? About how long is the 1/2" supply pipe?

 

Might be better to use a low flow shower head at least in winter, caravan accessories places should do them.

 

Still, if you'd bought a new Morco which behaved *exactly* the same you'd be pretty p*ssed off wouldn't you?

 

I'd look into making a counterflow heat exchanger out of copper pipe, to recover heat from the shower waste water to 'temper' the cold water going into the heater.

 

cheers,

Pete.

[paulcatchpole]

Still, if you'd bought a new Morco which behaved *exactly* the same you'd be pretty p*ssed off wouldn't you?

 

Mind you, Alan's *used* to work properly, so the question has always been, what's changed?

 

My D61E, even with a restricted water flow into it due to a plugged filter in line, produces a suitable squirty shower, at a temperature which is too hot for me - but typically just right for Kate. I've no idea what the shower head is, but it looks fairly typical house fare. Maybe I'll get an unpleasant surprise when I replace the bathroom in a fortnight, fitting a normal bath shower mixer...

 

Alan, does the thing actually fire up fully - i.e. roaring away nicely, in a deafening way? If so, it's hard to imagine cool water coming out of it! I had problems with mine being reluctant to fire up as a result of poor water flow through it, due first to a knackered pump, then to the plugged filter, but your pump is performing fine, so it can't be that - unless it isn't firing up fully and that's being caused it by it not thinking the water flow is good enough?

 

Thinking aloud and probably confusing things, sorry!

 

PC

[smileypete]

Mind you, Alan's *used* to work properly, so the question has always been, what's changed?

The weather? :

 

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'd expect it always worked properly in summer.

 

 

Assuming the heater itself is OK, the other things I'd investigate are the gas supply and water pressure.

 

If the cooker is part way along the supply it might be worth measuring the gas pressure drop at the heater with the heater is off and the cooker is off/on partly/on full. If there's little or no 'sag' then it points to a restriction between the cooker and heater.

 

Also of interest is the stated capacity of the pump in lpm, and it's 'open flow' rate from a fully open tap compared to this.

 

cheers,

Pete.