All pipework replaced - still little to no heating downstairs

[knightime]

Hi,

Yesterday we had all the pipework for our central heating replaced, as we were having an issue with the rads downstairs not working (after a recent rad replacement and power flush).

When the guys left yesterday all the rads were working - we had full heat in all rads - boiling hot! We had the central heating on till around 10.30pm before shutting the system off.

However this morning, when the central came on, only the hallway rad was on, and it was barely hot. The rads for the dining room and the lounge were stone cold.

I dialed back the lockshields for the rads upstairs, as they were left fully on, and am confident they're nicely balanced as there's good heat coming out of them. The flow pipes into the rads upstairs are roasting hot.

The flow to the rad in the hallway is hot, not roasting, but hot. I've checked the pins on the TRVs on the two rads in the other rooms and they're pushing down/popping up ok i.e. not stuck. The lockshields on the rads downstairs are also fully open.

I checked the main flow pipe from the boiler to the heating downstairs - the pipe is boiling hot. But the return is cool to touch - not stone cold but not warm either.

I'm trying to get hold of the plumber but he's not answering, so will try again later.

In the meantime does anyone have any suggestions as to why, with new pipework, and with the rads working fine yesterday, they've suddenly stopped?

Any advice would be greatly appreciated!

 

[newcastle phill]

Possible air lock ???

Try and call the guy back but failing that make a note of the lockshield positions and turn the upstairs off and try and force the water around the downstairs, if it comes on let it run for a while and bleed off if necessary. Then re open upstairs to the correct noted positions. Failing that is it balanced correctly ?

 

[knightime]

Thanks newcastle phill for the advice, we'll try that now!

 

[knightime]

Hi newcastle phill - ok, we did what you suggested, but now the only rad that was downstairs has stopped working - the flow pipe into it is cooling! Just checked the main flow to downstairs and it's still hot - am completely stumped! I've made contact with the plumber so there's a start - will let you know what he thinks - any further suggestions though?

 

[oz-plumber]

Check to see which pipe is hotter on all rads.

The lockshield side should be noticeably cooler.

Hopefully they have connected each radiator correctly, with the flow to the control side and the return to the lockshield side

 

[knightime]

It appears the connections are OK - the pipes to the thermostats were the ones that were boiling hot - the lockshield pipes were a lot cooler.

 

[newcastle phill]

Try putting one on at a time upstairs and see if it comes back on.
That sounds like a piping issue. See what the plumber says on his return...

 

[knightime]

Ok, will do!

 

[knightime]

Started with the rad in the bathroom - no joy. Interestingly the flow pipe to the downstairs rads is not scalding hot any more - I can hold it without it burning. So it appears shutting off all rads upstairs (shields and thermos) is having a negative effect on the flow to downstairs. I'm now just trying the rad in bedroom 1...

 

[knightime]

No joy from bedroom 1 - now onto bedroom 2. Incidentally, bedroom 2 is being fed from the same flow/return pipes as bedroom 1 (they said that's how it was piped previously and shouldn't make a difference). I'm guessing that's correct?

 

[knightime]

Just spoke to the plumber - he said it should all be working as it's brand new pipework. The only thing he wasn't able to change was the flow/return pipe directly from the boiler to upstairs (as it was under the bath) - those pipes were copper, and cut just in from of the sink. They then connected 22m plastic tubing which the tee'd off to downstairs/upstairs feeds. However I said that if it was an issue with the piping under the bath, then surely upstairs wouldn't be working, as it appears the flow and return upstairs seems fine. Is that a fair assumption, or could there be an issue with the pipework under the bath I wonder?

 

[SimonG]

Anybody looked at the pump? Definitely sounds like a circulation issue. Also on the trv's, just because the pins move up and down doesn't mean they are not stuck. Its the guts that stick and not the pins.

 

[knightime]

Hi Simon - no, the pump hasn't been investigated yet. You're absolutely right - it definitely sounds like a circulation issue now - the plumber originally thought it was a blockage I the pipework, which is why he recommended brand new piping. But as it's doing exactly the same thing as before, it appears the pipework was not at fault. When I see him tomorrow shall I suggest a pump replacement for you think? IBM still testing the lockshield isolation that Newcastle suggested above - may have to start again as I only partly opened the lockshields while testing - doh!

 

[1Steven]

Hello, how old is the pump and what model and make is it?

 

[knightime]

Hi all. Ok, I put the radiator on in bedroom 3, which is the one furthest from the boiler, and the flow pipe running to the downstairs rads is scalding! The flow pipe to the rad in the hallway is hot - not scalding, but hot, and the rad in the hallway is warm(ish). I have no idea what this indicates.

As far as what the plumber showed me, the pipes exit the boiler, meet a tee in the top hallway, tee off to downstairs then carry on to supply heating to the top floor. Why shutting off all rads upstairs would interfere with the tee off to downstairs I don't know. Or why turning on the lockshield in bedroom 3 would let hot water flow downstairs (when that flow should be independent).

1Steven, the boiler is a Potterton Main Combi condensing boiler which is approx 4 years old with original working parts. They removed the pump when they did the powerflush, then reinstalled it - not sure of it's model number. Could it's removal/re installment be causing a circulation issue?