Reverse Circulation

[blackbirdxx]

I had a completely new S plan pressurised central heating system installed 6 months ago with new rads, pipes and boiler. Ever since it was installed, its suffered from reverse circulation with the upstairs rads getting warm with the HW switched on/CH switched off.
The only way to sort this problem properly is to remove the HW cylinder and re-pipe the connections. It has been suggested by the plumber that it can be resolved easily by installing a pressure relief valve which will negate the need to remove the cylinder. I'm not so sure about this proposal and whether I should be accepting this on a new installation. It sounds a bit of a bodge and something else to go wrong? The prv will be under the floorboards. What do you guys think??
Anyway, thanks to all in advance...

 

[fixitflav]

The only way to sort this problem properly is to remove the HW cylinder and re-pipe the connections.

From that, it sounds like you're aware that the heating return pipes must be commoned before joining the HW return. The installer ought to have known. I think you should insist on him putting it right.

 

[Madrab]

Yup, HW return needs to be last tee on the circuit to avoid convection/reverse circulation into the rads when HW is calling.

Any other fix (Never heard of a PRV being used to fix it tbh, if anything it would be a non return valve and even then it's a bodge) goes against the correct design of an S Plan Heating and HW system.

 

[ianmcd]

A Prv wont do anything, and why would he need to take the cylinder out ? just make the HW return the last connection on the return circuit

 

[blackbirdxx]

Sorry guys, I meant non return valve....not prv.
I think the consensus from your answers is to remove the HW cylinder and do the job properly.

 

[blackbirdxx]

and why would he need to take the cylinder out

The cylinder sits on a board and the connections are below this. I'm told the cylinder must come out to get to the correct pipework.

 

[ianmcd]

The cylinder sits on a board and the connections are below this. I'm told the cylinder must come out to get to the correct pipework.

doubt it very much, he just needs to find the return blank the existing connection and extend it to the last connection in the circuit

 

[ericmark]

Question is if reading correctly "Should you allow your plumber to cure the problem?" If you stop the plumber doing what he wants, what will then happen? It does not really matter what should be done, if you stop him doing what he wants, who is going to correct it?

I had the problem with a C plan where there are no motorised valves, but water can flow through a pump which is stopped, but flowing though a motorised valve that would be hard, some thermal syphon within large bore pipe work maybe, but my daughter had a Y plan and the motorised valve micro switches went faulty, so to keep it going the bleed lever was latched to half open, which means every time the boiler switched on to do domestic hot water it also heated the radiators a little, but it switched on to heat the DHW so few times, she did not notice the radiators got warm.

So big question is will the non return valve stop the fault? Seems likely some thing else wrong. If getting reverse flow not just some convection then it seems likely some thing else it wrong. But why get involved, up to plumber to fix, and if you tell him how to do his job, be it right or wrong will he say told you that would not fix it, so down to you?

 

[Madrab]

+1 with @ianmcd , it is as simple as connecting the return from the cylinder into the main return after the last return connection from the radiator circuit. They have made a fundamental fau pas when they installed the system and should be putting it right, at their cost. Any decent installer worth their reputation should guarantee their pipe and install work for at least a year.

Even if he is saying that he wants to take the cylinder out to fix this then that's down to him, they did it wrong so whatever they think they need to do to correct the issue then let them fire away, just don't let them charge you for it.

That being said I think he may be saying that to make it sound like it would be a 'mare to fix properly (cylinder out sounds really extreme to any normal consumer) that way you don't press them to do it correctly and let them fudge it with a valve that could fur up further down the line.

 

[blackbirdxx]

Hi,
Just to clarify, this is a second plumber who has been appointed to solve the problems created by the first. The second plumber is saying that the cylinder should be removed to access the pipes below to do it correctly. The original plumber is saying it all can be sorted with a non return valve but at the end of the day he is being recharged the rectification costs as he was the plumber subbed to a builder who installed the system. Don't know why the original plumber won't come back to correct his work, I think some issue with the builder, but who knows... .



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[blackbirdxx]

Pls ignore the attachments, not sure how they got uploaded...

 

[blackbirdxx]

Now that the problem has been diagnosed by the second plumber to remove tank, replumb and refit tank, he is proposing to charge me £1240+VAT to do the work. Is this a reasonable cost? Seems a lot to me for 1 days work, but may be the going rate? At the end of the day, the original plumber is being recharged this cost.

 

[ianmcd]

You are being ripped off and how are you going to recharge the existing plumber ? have you already paid him ?

 

[fixitflav]

Now that the problem has been diagnosed by the second plumber to remove tank, replumb and refit tank, he is proposing to charge me £1240+VAT to do the work. Is this a reasonable cost? Seems a lot to me for 1 days work, but may be the going rate? At the end of the day, the original plumber is being recharged this cost.

I'm not in the trade, so no idea, but I suspect the pros will say without knowing the layout of your house it's impossible to say. There could be a fair amount of work involved, whether or not the cylinder has to come out. The first house I bought (new) the boiler was in the kitchen, the upstairs rads return came down, the downstairs up from the floor, commoned near the boiler in the kitchen. The cylinder return was brought close to the same point. As it happens, the HW return was connected before the rads return commoned, only a few inches apart, and I got your problem. When I told the builders they easily fixed it. If your cylinder return is just connected near the cylinder, there could be a fair length of pipe needed, maybe not easy to route.
Still don't see why the cylinder needs to come out. As others have said, just need to cut the cylinder pipe, blank the bit that goes to the network, and run a pipe from the cylinder to a point after all the rads returns are commoned.

And are you happy you'll get the £1240 back from the first plumber?

 

[blackbirdxx]

You are being ripped off and how are you going to recharge the existing plumber ? have you already paid him ?

Haven't paid him yet to do the work as I'm waiting to hear via a builder if the first plumber is prepared to pay this cost. I'll get the money back at the end of the day as this is part of an insurance claim which has used a builder appointed by the insurer.
Just wondered what a reasonable cost is to remove a tank and replace it, including draining and refilling?? Only a short length of pipe is required to connect to the boiler return once the cylinder is removed. Bear in mind I do live in outer London.