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Main Combi 24 HE Hot Water Luke Warm Following Water Being Cut-Off

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Discuss Main Combi 24 HE Hot Water Luke Warm Following Water Being Cut-Off in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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M

Magic

Hi All,

I'm new here so thanks in advance for any help :)

I have a Main Combi 24 HE running on propane in a mobile home. I moved into the home in March and was told that the boiler was just a few months old, it certainly looks all clean and sparkly and has always worked well enough that I can run a little cold with the hot fully open to get a nice hot bath.

I am an electrician with a good understanding of plumbing, just not combi boilers! So, here goes......

Last week my water supply was disconnected without warning, at the time I was running a bath and my washing machine was on. Since then my hot water is only coming out luke warm. My central heating works okay, although I do think that it is a little slower to heat the rads but I'm not 100% about this.

Also, there is a noise a little like a rattlesnake when hot water is being called for. This appears to be coming from the plate heat exchanger, but again I'm not 100% about this. There is no noise when the central heating is on.

If I restrict the flow at the hot tap the water does get a little hotter, enough to bath in but only just and next month the water going in will be colder.

If I turn down the temperature dial on the front of the boiler then the flames do drop and return to what appears to be 'full-blast' when I turn it up again.

I have drained the boiler down a couple of times, hot water side only, but this has not changed anything. So, does anyone have any suggestions?

Many thanks for reading my plea :)
 
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Most like to be something has gone up the mains supply pipe when it was turned off.
Who turned the water off & why ??
Ask them (if it was a plumbing company) to come & sort out the problem they caused!
Otherwise get in a GSR engineer.
BTW Welcome along Mr Sparks, another one come over from the dark side. :smile5:
 
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Restrict the flow of water to around 2 gallon per minute and see how it heats.
All 24kw combi's can heat around 2gpm with a 35º temperature rise. If you are not getting that phone whoever had the water off or your local gas man.
 
tamz said:
Restrict the flow of water to around 2 gallon per minute and see how it heats.
All 24kw combi's can heat around 2gpm with a 35º temperature rise. If you are not getting that phone whoever had the water off or your local gas man.
Click to expand...
Mr Tamz, can you please use the SI (didn't want to put English for fear of upsetting you) units for water flow, what's with the 2gpm ? Pints & Gallons (along with Feet & Inches) went out when even you were a nipper LOL :winkiss:
 
chris watkins said:
Mr Tamz, can you please use the SI (didn't want to put English for fear of upsetting you) units for water flow, what's with the 2gpm ? Pints & Gallons (along with Feet & Inches) went out when even you were a nipper LOL :winkiss:
Click to expand...

You not uom ambidextrous Chris? Must be my age :)
 
When did this start Chris:lol:

Most people over about 30 haven't a clue how to visualise things in a metric perspective (regardless of what the bbc say).

If someone told me they weighed 80kg i'd have to multiply it by 2.2 then divide it by 14 then take the point whatever and multiply that by 14 to get how many pounds (12st8lb) to convert it to stone and pounds to have an idea of the weight.
How big is a 200g steak you buy in the restaurant? Not big enough for what you are paying for it when you work it out it is under half pound (7oz).
If you said you lived 500km away i'd have to multiply it by 5 and divide by 8 to have a clue how far away you were but then again i'm fine with metres and mm.
I buy petrol in litres and convert it to how much a gallon (£6.30/g ridiculous!)
I can cope with celcius ok but have to convert it to real money for the old folks (multiply by 9 divide by 5 and add 32).

At least it keeps my brain active :smile:
I'll away and see if i still have my ¼ of peppermints still in the cupboard :lol:
 
God help me! I'm of the age that works in both old and new moneys!
 
As above me to, it was hell working with both at the same time during the cross over period.
 
Oh dear............what did I do?

Right, now the serious bit. Thanks for your replies guys.......

I share a water supply with a bungalow next to me, I believe that is was cut-off to have a new kitchen sink plumbed-in. I have met the guy doing it and he's a bit of a clown (I don't mean that he's quite funny and good at entertaining children). I expect that there are now 20 compression joints under the sink and he'll have to do it again when he realises that there's no supply for a washing machine.

That said, the water supply T's off in different directions for us and I cannot see how any crap has gone down the pipe and ended-up in my boiler. I really think that we are just dealing with air, but I will ask him exactly what he has done and report here.
 
Sediment will sit in the bottom of the pipe and when the supply is re-established the force of the water through the pipes can stir it up and into essential bits and pieces.
 
One other thing. As I was running a bath at the time the water was cut-off it is probable that the burner was going when the hot water pipe went dry at the heat exchanger (if I understand how combi boilers work correctly?). Could this have caused any damage?
 
No the burner would have cut off as soon as the flow stopped (flow switch)
 
tamz said:
When did this start Chris:lol:

Most people over about 30 haven't a clue how to visualise things in a metric perspective (regardless of what the bbc say).

If someone told me they weighed 80kg i'd have to multiply it by 2.2 then divide it by 14 then take the point whatever and multiply that by 14 to get how many pounds (12st8lb) to convert it to stone and pounds to have an idea of the weight.
How big is a 200g steak you buy in the restaurant? Not big enough for what you are paying for it when you work it out it is under half pound (7oz).
If you said you lived 500km away i'd have to multiply it by 5 and divide by 8 to have a clue how far away you were but then again i'm fine with metres and mm.
I buy petrol in litres and convert it to how much a gallon (£6.30/g ridiculous!)
I can cope with celcius ok but have to convert it to real money for the old folks (multiply by 9 divide by 5 and add 32).

At least it keeps my brain active :smile:
I'll away and see if i still have my ¼ of peppermints still in the cupboard :lol:
Click to expand...
As ever a full & information packed reply Tamz.
Although it irks me to admit it, I have to agree with you on the body weights & long distances but alright with the others.
I just wonder how long the imperial units are going to survive when I see young en's using inches cos the guy on site does ??
Now where did I leave my 1/2 pound of black current liquorice !!!
 
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It is a strange one Chris. I think weights will come first as the younger ones don't really know lb and oz and have no real reason to use them.
Pints and gallons may be next but feet and inches and miles will probably last for another generation at least but only some units. Most don't know what a yard is or how many yards are in a mile never mind how many chains are in a furlong :lol:
The same could be said for some SI units. No one uses deciliters or my favourite waste of time the decimeter.
 
Love it when a post diverts with humour but quite what the OP thinks of us I shudder to think.
 
tamz said:
I've never seen them for years! I loved them when i still had teeth :lol:
Click to expand...

Can still get them over here. There's a sweetie shop round the corner of the tool shop (which has my nose print on the window....) that still sells sweeties by the quarter out of the jar. I'll send you some over if you want Tam.
 
I've told the good lady that her project for tomorrow is to scout out the sweetie shops to find some.
I'll let you know if she fails :smile:
 
chris watkins said:
As ever a full & information packed reply Tamz.
Although it irks me to admit it, I have to agree with you on the body weights & long distances but alright with the others.
I just wonder how long the imperial units are going to survive when I see young en's using inches cos the guy on site does ??
Now where did I leave my 1/2 pound of black current liquorice !!!
Click to expand...

People should be shot for using imperial.
 
Okay, I'm loving the side conversations here lol.

But about my problem again...... :)

If there is some crap in the heat exchanger then wouldn't that have the same affect as restricting the flow? i.e. less water coming through but it would be hotter?

When the hot is on then the flow is a bit 'up and down', if that's another good clue.

Liking the chat guys
:yesnod:​
 
Magic said:
Okay, I'm loving the side conversations here lol.

But about my problem again...... :)

If there is some crap in the heat exchanger then wouldn't that have the same affect as restricting the flow? i.e. less water coming through but it would be hotter?

When the hot is on then the flow is a bit 'up and down', if that's another good clue.

Liking the chat guys
:yesnod:​
Click to expand...

There are some things that spring to mind I would check but the advise would be of the kind I can only share with other gas safe in the non public forum. But suffice to say that your understanding that any blockage would reduce flow is logical but the reduced flow may be almost un noticeable. Call a local GSR. If you have the means to measure the flow and temperature of the hot water the Main is putting out, as has been suggested it will be clear if it is underperforming.
 
tamz said:
It is a strange one Chris. I think weights will come first as the younger ones don't really know lb and oz and have no real reason to use them.
Pints and gallons may be next but feet and inches and miles will probably last for another generation at least but only some units. Most don't know what a yard is or how many yards are in a mile never mind how many chains are in a furlong :lol:
The same could be said for some SI units. No one uses deciliters or my favourite waste of time the decimeter.
Click to expand...

U live in a posh area then. When I was a student learned all about 1/8ths and Oz
 
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