22mm non-return valve on CH system

[moosehead]

I wonder if any of you can advise why my CH system would have a non-return valve within it?

For some time now three radiators ahve not been heating at all and I decided to investigate today as we are about to have some decorating done. (Usually I do these things int he middle of winter and am without CH for a week).

The NR valve is in amongst a spaghetti junction of pipework and I recall we used to have a separate pump and relay for a conservatory which we no longer have. The valve was on the flow side and , needless to say, it was not functioning correctly.

Can I just chop it out?

Any advice apprciated.

 

[gas4you]

These are usually fit to prevent a gravity circulation around radiator circuits when they are not supposed to be on. eg on an old gravity primary system you would have one fitted to the ch flow so that the upstairs rads would not get hot when just hot water was selected.

If you have a fully pumped system then it is possible you may not need it, but without seeing your installation we on here can only guess why it has been fitted.

 

[chrishutt]

Non return valves are usually fitted to stop gravity circulating in the CH pipework, but might also be fitted in conjunction with a second pump. We really need a pic or diagram of pipework arrangement to say for sure, but it sounds like you could remove it.

 

[moosehead]

Thanks Dave.

This is a fully pumped system, used to be gravity.

 

[moosehead]

Chris - not sure how to post a pic, however, the more I think about it it's probably as a result of the second (now removed) pump.

We have had the house extended and the NR valve is on the side of the old part of the house separating the house from the now removed conservatory.

I think what I will do is remove and replace with a 22mm connector - fire up the system and see what happens.

Thanks for your help and I'll post back with the outcome.

Cheers

 

[moosehead]

Post script -

Remoed the non-return valve and replaced with a 22mm straight connector - bingo - the three dead rads are now glowing. No adverse effects I believe - just one comment - is it usual to have a little heat radiating back from the emersion along the return pipe of the CH when only hot water is being called for at the boiler?

Thanks again fro your help one and all.

 

[ACOperson]

As the guys have said twice, the non return valve is designed to stop this heat radiating down the Ch return when only hot water is selected.

It was installed there for a reason!

Check that the old non return valve is opening and closing correctly, if not, replace it with a new non return valve which works.

 

[moosehead]

As a matter of interest should the nr valve be on the flow or return?

 

[gas4you]

Depends on ther reason/fault it is preventing.

 

[moosehead]

Have just run anoither check - no heat coming back up the CH return - must've been residual heat from test the CH. As a matter of interest the NR valve was on the flow side and I am sure it was there because of a second pump per chrishutt.

It has taken three years to sort this out. The old valve was inacessible from above, it's only because we are having our ceiling made good/replastered that I finally decided to investigate the pipework by hacking one section of the ceiling plasterboard.

Looking at the old valve it is a pretty sorry sight.

Just need the whole system re-balanced now!

Cheers

 

[moosehead]

One final post script on this subject which may be of some use to both diy'ers and pro's alike.

I now know the reason why our three rads were 'dead' - the NR valve, however, I recall when our house was extended the plumber had to move the boiler to a new position and in doing so reversed the flow through the system (intentionally or unintentionally I don't know), it was at that point that the three rads died. He was never to know there was a NR valve as it was hidden under floor boards which he had no reason to know existed.

I feel that CH and HW systems should have some form of service manual, similar to a car log book, which shows the system lay out and any alterations thereto over it's lifetime. Think of how efficient running and repairing a system would then be.

 

[Dan Robinson]

I feel that CH and HW systems should have some form of service manual, similar to a car log book, which shows the system lay out and any alterations thereto over it's lifetime. Think of how efficient running and repairing a system would then be.

There are to a certain extent, but that ssumes that people followed established norms when they fitted a system. Hoever, every property is slightly different - even the rabbit hutches they are throwing up nowadays.

There is no accounting for things like your situation, as you said, the poor plumber probably would never have found that NR in the normal scheme of things.