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Morco 61B and Hot water to Shower


Surfingboat

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Hi, I have a Morco 61B boiler that is fed with water via a Shurflow 30 PSI (2 bar) diaphragm pump. The boiler requires a minimum of 1 Bar before the gas valve opens and it will start to heat any water fed to it and I have a 2 bar pump feeding it.

 

When the boiler ignites and starts to heat the water, the pump starts to cycle (turn on/turn off rapidly), this causes the water to go cold then hot as the pressure to the boiler drops in and out and the boiler keeps igniting/shutting down. I cannot get a steady flow of hot water. If I open the cold tap, the pump stops cycling and the pressure and flow of water is good, except the water is now cold/luke warm.

 

If I turn down the the temperature dial on the boiler, i can get a constant supply of warm water to the sink, but not the shower, and at a very slow flow rate. If I try to increase the temperature dial on the boiler, the pumps starts to cycle again and the boiler cuts out and reignites with each cycle. The problem seems to relate to increasing the temperature on the boiler, i can get cold and luke warm water with ease :)

 

I have checked the flow rate and it is 6 litres per minute as specified on the Morco website. 

 

Does anyone have any pointers? I have been looking at fitting a FIAMMA A20 Expansion Tank - Accumulator Tank. 

 

Thank you (off to bed now but will see any replies on Sunday)

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Yes, you probably just need an accumulator tank. Many boats have them fitted to help with pump cycling even though they don't have instant gas water heaters. 

 

I have the same water heater, a Parmax 3 pump and an accumulator fitted just after the pump and the heater works fine.

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8 hours ago, Surfingboat said:

When the boiler ignites and starts to heat the water, the pump starts to cycle (turn on/turn off rapidly), this causes the water to go cold then hot as the pressure to the boiler drops in and out and the boiler keeps igniting/shutting down.

 

Firstly this pump cycling needs to be fixed. Fitting a correctly pressured accumulator on the pump outlet will stop the pump cycling. I'd suggest an accumulator of about four or five litres in capacity, and make sure it is for potable water not for central heating. There is a loose colour coding convention that white or blue = potable water and red = central heating but manus don't all conform to this. I've seen silver/grey accumulators recently that can be either and white that are CH. 

 

Secondly I'm not convinced the burners dropping in and out is a direct result of the cycling. All three of mine do this too if the flow rate through them is too low and the tank water slightly warm (e.g. in summer heatwave) and the flame size control knob is set to "High", and I have accumulators! I think there is some sort of mechanical overheat protection built into the Morcos coming into operation. Try running yours on "low flame" instead of "high flame".

 

Try all this with the Morco temp control set to Max. Turning the temp control down misleads the user as it appears to simply bleed some cold water into the  already possibly overheated heated output from the Morco. 

 

 

 

 

 

Edited by Mike the Boilerman
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9 hours ago, blackrose said:

Yes, you probably just need an accumulator tank. Many boats have them fitted to help with pump cycling even though they don't have instant gas water heaters. 

 

I have the same water heater, a Parmax 3 pump and an accumulator fitted just after the pump and the heater works fine.

Thank you Blackrose, I will purchase an accumulator tank then

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1 hour ago, Mike the Boilerman said:

 

Firstly this pump cycling needs to be fixed. Fitting a correctly pressured accumulator on the pump outlet will stop the pump cycling. I'd suggest an accumulator of about four or five litres in capacity, and make sure it is for potable water not for central heating. There is a loose colour coding convention that white or blue = potable water and red = central heating but manus don't all conform to this. I've seen silver/grey accumulators recently that can be either and white that are CH. 

 

Secondly I'm not convinced the burners dropping in and out is a direct result of the cycling. All three of mine do this too if the flow rate through them is too low and the tank water slightly warm (e.g. in summer heatwave) and the flame size control knob is set to "High", and I have accumulators! I think there is some sort of mechanical overheat protection built into the Morcos coming into operation. Try running yours on "low flame" instead of "high flame".

 

Try all this with the Morco temp control set to Max. Turning the temp control down misleads the user as it appears to simply bleed some cold water into the  already possibly overheated heated output from the Morco. 

 

 

 

 

 

Thank you Boilerman, for the detailed reply. I am going to try what you suggested in your post today and will report back with the results later this afternoon. This is the current portable water accumalator I have saved on my ebay watch list

 

https://www.ebay.co.uk/itm/Accumulator-Expansion-tank-suitable-for-POTABLE-DRINKING-WATER-8-litre-ACC8Z/111199557398

 

But, can this be positioned horizontally? Do you know?  I have seen this adaptable pipe work which makes it look like it is T'eed off the water outlet after the pump.

https://www.ebay.co.uk/itm/ACCUMULATOR-TANK-WATER-SYSTEMS-SPEED-FIT-CONVERSION-KIT-BRASS-WITH-15mm-TEE/292813108705

 

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6 minutes ago, Surfingboat said:

Thank you Boilerman, for the detailed reply. I am going to try what you suggested in your post today and will report back with the results later this afternoon. This is the current portable water accumalator I have saved on my ebay watch list

 

https://www.ebay.co.uk/itm/Accumulator-Expansion-tank-suitable-for-POTABLE-DRINKING-WATER-8-litre-ACC8Z/111199557398

 

But, can this be positioned horizontally? Do you know?  I have seen this adaptable pipe work which makes it look like it is T'eed off the water outlet after the pump.

https://www.ebay.co.uk/itm/ACCUMULATOR-TANK-WATER-SYSTEMS-SPEED-FIT-CONVERSION-KIT-BRASS-WITH-15mm-TEE/292813108705

 

 

That accumulator is 8 litres. It will work fine but is far bigger than you need. 3 or 4 litres will be fine, and cheaper. Some need to be mounted vertically, others don't. I've never figured out why or which I'm afraid. Best to mount vertically with the Schrader valve at the top for easy access. It will need recharging periodically. 

 

My expansion vessels are screwed into fittings like this, which are in turn, screwed to a horizontal plywood base.

 

s-l500.jpg

 

https://www.ebay.co.uk/itm/15mm-Compression-x-1-2-BSP-Brass-Outside-Tap-Wall-Plate-Tee/122981629279?hash=item1ca246bd5f:g:CkoAAOSwwgtajvJl

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Yes, perfectly OK for it to be horizontal.

 

In my view best attached to wherever it tees of the cold pipe by a flexible tap connector of some type.

 

The connector to the accumulator is parallel threaded, so easiest way to make a seal is to use a tapo connector that incorporates a fibre or plastic washer.

 

Please don't ask how I know other methods don't work as reliably!

1 minute ago, Mike the Boilerman said:

 

Some need to be mounted vertically, others don't. I've never figured out why or which I'm afraid.

 

Hard to understand why if it is a standard type with a diaphragm?

 

Can't see how it can possibly make a difference?

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18 minutes ago, Mike the Boilerman said:

 

That accumulator is 8 litres. It will work fine but is far bigger than you need. 3 or 4 litres will be fine, and cheaper. Some need to be mounted vertically, others don't. I've never figured out why or which I'm afraid. Best to mount vertically with the Schrader valve at the top for easy access. It will need recharging periodically. 

 

My expansion vessels are screwed into fittings like this, which are in turn, screwed to a horizontal plywood base.

 

s-l500.jpg

 

https://www.ebay.co.uk/itm/15mm-Compression-x-1-2-BSP-Brass-Outside-Tap-Wall-Plate-Tee/122981629279?hash=item1ca246bd5f:g:CkoAAOSwwgtajvJl

Right on, i will look for a smaller one, and thanks for the link, very helpful

18 minutes ago, alan_fincher said:

Yes, perfectly OK for it to be horizontal.

 

In my view best attached to wherever it tees of the cold pipe by a flexible tap connector of some type.

 

The connector to the accumulator is parallel threaded, so easiest way to make a seal is to use a tapo connector that incorporates a fibre or plastic washer.

 

Please don't ask how I know other methods don't work as reliably!

 

Hard to understand why if it is a standard type with a diaphragm?

 

Can't see how it can possibly make a difference?

Thanks for the reply, i am glad it can be positioned horizontally as I don't have a lot of room to fit it

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23 minutes ago, Surfingboat said:

Thanks for the reply, i am glad it can be positioned horizontally as I don't have a lot of room to fit it

Well with the caution that mike says some can't!

He is a lot more experienced in this kind of thing than me, so I guess you need to check somehow that the one you buy can.

...Which may be hard, as they don't tend to come with much information, or any instructions, in my limited experience, (based on a sample size of 4, I think).

I still can't think of any scientific reason why some should place such a restriction, though.

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16 minutes ago, alan_fincher said:

I still can't think of any scientific reason why some should place such a restriction, though

 

Well there are to ways of making one aren't there? The diaphragm is no such thing really, it is a bag like a football bladder. So you can arrange the bladder inside the metal chamber to be filled with air and the chamber fill with water around it, or you can connect the bladder to the water and pump air into the outer chamber. 

 

One type I believe, needs to be fitted vertically and the other works in any attitude. Typing this though I can't for the life of me figure out which would be which!

 

 

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3 minutes ago, Mike the Boilerman said:

 

Well there are to ways of making one aren't there? The diaphragm is no such thing really, it is a bag like a football bladder. So you can arrange the bladder inside the metal chamber to be filled with air and the chamber fill with water around it, or you can connect the bladder to the water and pump air into the outer chamber. 

 

One type I believe, needs to be fitted vertically and the other works in any attitude. Typing this though I can't for the life of me figure out which would be which!

Could there be a type where the bladder is a diaphragm that’s attached to the circumference of the tank? That wouldn’t like to be on its side. 

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2 minutes ago, WotEver said:

Could there be a type where the bladder is a diaphragm that’s attached to the circumference of the tank? That wouldn’t like to be on its side. 

 

Yes there could actually. Good idea! Some vessels have a welded waistband, others the centreline joint is crimped. The crimped type might be gripping a flat diaphragm. I've never chopped a dead one open to find out. Its on my (long) list if things to do in my spare time!

 

 

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16 minutes ago, WotEver said:

Could there be a type where the bladder is a diaphragm that’s attached to the circumference of the tank? That wouldn’t like to be on its side. 

 

Why?

 

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Some smaller accumulators for marine use at one time had nothing separating the air and water so those had to be mounted vertically and it was also a good idea to remove them anally and shake out ant water so they refilled with air.  think Jabsco made one.

Edited by Tony Brooks
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1 hour ago, alan_fincher said:

Why?

Because it would be ‘sagging’ from the ‘top’ of the vessel instead of having equal tension all around the circumference. 

 

 

Edited by WotEver
Changed pressure to tension ‘cos it didn’t make sense
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Good, glad you solved it. I fitted an isolator on the T to my accumulator so that if I'm trying to identify whether the system is leaking I can isolate the accumulator and it makes it easier to listen for pump cycling.

 

One question from me: What are the low flame, high flame settings on the Morco boiler for? Presumably this doesn't affect the water temp as that is set by a different knob.

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2 hours ago, blackrose said:

Good, glad you solved it. I fitted an isolator on the T to my accumulator so that if I'm trying to identify whether the system is leaking I can isolate the accumulator and it makes it easier to listen for pump cycling.

 

One question from me: What are the low flame, high flame settings on the Morco boiler for? Presumably this doesn't affect the water temp as that is set by a different knob.

I am not sure. I know if i turn the dial to the high flame symbol, this would cause the pump to cut in and out until the accumalator was fitted. I am guessing it just heats the water to a higher temperature. 

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45 minutes ago, Surfingboat said:

 

I am not sure. I know if i turn the dial to the high flame symbol, this would cause the pump to cut in and out until the accumalator was fitted. I am guessing it just heats the water to a higher temperature. 

 

In that case temperature setting must be a combination of both the temperature and flame height adjustment?

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On ‎21‎/‎07‎/‎2019 at 11:21, Mike the Boilerman said:

 

Yes there could actually. Good idea! Some vessels have a welded waistband, others the centreline joint is crimped. The crimped type might be gripping a flat diaphragm. I've never chopped a dead one open to find out. Its on my (long) list if things to do in my spare time!

 

 

Mike,

The crimped vessels have a diaphragm, air on one side, water on the other. Heating vessels are usually this 'cheap' construction and regularly fail. Potable vessels usually have a screwed flange retaining a bladder; good ones  can have spares fitted. The water is passed into the bladder, and the case is pressurised. The welded seam is just a seam, but it helps a mounting bracket hold it.

3 hours ago, Surfingboat said:

 

I am not sure. I know if i turn the dial to the high flame symbol, this would cause the pump to cut in and out until the accumalator was fitted. I am guessing it just heats the water to a higher temperature. 

The Morco has the two knobs, The top one is a gas governor and varies the amount of gas passed to the burners. The lower one is a water governor which varies the amount of water passed through the heater. It is a good idea to turn this weekly just to stop it seizing as it is just a valve in the water flow.

Edited by Ex Brummie
To correct my reply
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42 minutes ago, Ex Brummie said:

The Morco has the two knobs, The top one is a gas governor and varies the amount of gas passed to the burners. The lower one is a water governor which varies the amount of water passed through the heater. It is a good idea to turn this weekly just to stop it seizing as it is just a valve in the water flow.

Thank you Ex Bummie, I did not know what the dials did exactly, so that thanks for explaining. 

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