REVERSE CIRCULATION

[blackbirdxx]

Hi,

I had an 'S' plan CH system installed by a plumber who was subcontracted to builder. Since it was installed, it has suffered from reverse circulation with the upstairs rads getting hot when the HW is switched on/CH switched off.

I am meeting with both the plumber and builder this week to try to finally agree a way forward and sort this problem. We do know the return pipework has been connected incorrectly beneath the HW cylinder but I'm afraid that the plumber will just propose a non return valve on the radiator return as an easy fix. I'm sure this will fix the problem but I don't want to be bullied into having to accept this 'bodge' solution on what is a newly installed system.

What are the feelings of you guys out there?? What are the problems of having a non return valve fitted, especially in the long term??
Many thanks in advance...

 

[Harry Bloomfield]

Make a start by checking the boiler manual, for which pipe is flow and which is the return. When first fired up, the flow should become warm/hot before the return pipe. Your upstairs rads getting hot with CH turned off, may have nothing to do with a reverse flow, more to do with wrongly piped up. Don't accept a compromise, quick solution - insist it is piped up correctly.

 

[blackbirdxx]

Don't accept a compromise, quick solution - insist it is piped up correctly.

Thanks, are there any issues with having a non return valve in place in the long term?

 

[Harry Bloomfield]

Thanks, are there any issues with having a non return valve in place in the long term?

If it is all plumbed up correctly with the electric valves in in the correct places, then no need for a NRV.

 

[blackbirdxx]

I'm just after a bit of ammunition for reasons why I don't want to accept a non return valve if that is what is being proposed. I'm sure that the builder will know nothing about CH and will simply agree with the plumber.

I'm thinking of the following reasons but not sure if they are relevant? Perhaps there are others?

1) valve furring up in time and stops working??
2) Inability to pressure clean the system properly??
3) Vibration??
4) Problems to future users who will not be aware of this valve under the floor??

There may be others??

 

[Harry Bloomfield]

1) valve furring up in time and stops working??
2) Inability to pressure clean the system properly??
3) Vibration??
4) Problems to future users who will not be aware of this valve under the floor??

Wait for Ian to pop in and reply with reasons..

 

[Agile]

It would help us to give you best advice of you explained what the problem is with the return pipework at the HW cylinder.

Most reverse ( or unwanted ) circulation seems to me to result from incorrect return pipework.

 

[Madrab]

@Agile

https://www.diynot.com/diy/threads/reverse-circulation.569944/

 

[blackbirdxx]

Hi,
Reverse circulation has been confirmed by another plumber attending site, see below:

 

[blackbirdxx]

Apologies, I'm not explaining myself very well....
I did not want to go over the possible reasons for reverse circulation as I this has been fully confirmed.

My question is about the possible problem of the original plumber pushing to use a non return valve as an easy fix rather than replumbing the return pipes. My question is what are my reasons for not accepting this approach without appearing overly awkward.

My suggestions would be as follows but I'm unsure if they are fully relevant/correct:

1) valve furring up in time and stops working??
2) Inability to pressure clean the system properly??
3) Vibration??
4) Problems to future users who will not be aware of this valve under the floor??

There may be others??

 

[Harry Bloomfield]

1) valve furring up in time and stops working??
2) Inability to pressure clean the system properly??
3) Vibration??
4) Problems to future users who will not be aware of this valve under the floor??

All of those reasons, plus...
5) It would be a botch to fix an issue he created.
6) You paid good money for the job done properly, to a professional standard. Why should you compromise?

 

[Agile]

I like to do things properly.

So I would take the view that correctly piping the return is the correct solution.

An NRV will prevent the problems in many cases but to me that is a bodge solution.

I also think that any contractor should be doing the job properly in the traditionally accepted manner in the first place and that any corrective work should aim to reinstate the system as it should have been done!

Plumbing training does cover this situation and those who have done it are taught the rules to be followed.

 

[blackbirdxx]

Thats great guys, just the confirmation I need..

 

[fezster]

As said already, apart from it being a bodge which should be enough reason to correct it properly for any professional, you may want to question whether a non-return valve is suitable to be used on a CH circuit long term.

 

[ianmcd]

I wouldnt accept a non return valve, just tell him you want the Return from the HW circuit to be the last connection next to the boiler return and you wont have any more problems