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!

 

[knightime]

*UPDATE*

The plumber came round today and removed the Spirotrap MB3 that had been fitted to the return pipe as he wanted to elimintae it from the equation. Unfortunately it didn't work. He's ruled out any issues with the boiler and believes that there must be an issue with the pipework that was done.

His reasoning is that both the flow and return pipes connected to the boiler are both scalding hot - in particular the return, which is much hotter than the flow! He thinks there must be a piping 'loop' issue, and the flow is just returning without circulating. The only thing he can't get his head around (and neither can I), is why the central heating worked for one day.

He will be coming back on 8th April to begin pipework connection diagnosis. I'll be taking pictures and assisting him, and will continue to update this post.

Cheers!

 

[knightime]

**UPDATE**

So, 2 months now without central heating...

The plumber is coming around again tomorrow to take a look at the pipework, but I've noticed something weird that I want to know if anyone can help with...

So I took up the floorboards in the bathroom and identified the flow and return pipes the original plumbers cut into. These of course lead from the boiler to service the central heating.

This morning I turned the central heating on and left it to run for an hour. The flow and return pipes that are directly connected to the boiler were both scalding hot. I went upstairs and identified the flow pipe, which was also scalding hot. But the return pipe was cold!!! How is this possible? If, as the plumber suspects, there's some issue with the original pipework and the flow is leading straight back to the boiler via the return and isn't circulating properly, how can the return pipe directly attached to the boiler be hot, but the return pipe upstairs in the bathroom be cold???

When I spoke to him just now he seemed as baffled by this as I was. Can anyone shed any light as to what might be going on? Once again the boiler is a Potterton Main Combi 30 Eco. The plumber asked me to look in the manual for an automatic bypass section but I couldn't see anything in there about that. The boiler isn't making any strange noises when the central heating is on and the pump has already been changed.

Cheers!

 

[Tonycane]

I would be chopping the flow and return and make a loop, add one rad at the end of the loop just to verify circulation. I'm still thinking it's a pipework issue.

 

[knightime]

The plumber believes that the pipe with the green paint is the flow as the other pipe had a Spirotrap on (which he removed last visit).

Both pipes are scalding when the heating is on.

 

[Howsie]

Get someone else in, this long without heating is unacceptable.

 

[knightime]

Here's the main flow an return upstairs in the bathroom.

The lower pipe (furthest away from the sink) is the flow as it gets scalding hot within 3 minutes of the central heating being on. The pipe above it is the return, which remains cold during the test I mentioned in the previous post.

 

[knightime]

I have Howsie - this is the 2nd plumber I'm on!

 

[knightime]

Cheers Tony - i'll pass that on to the plumber tomorrow!

 

[Tonycane]

Can't see the pic, can you get to the pipe work directly above the boiler and show a pic?

 

[knightime]

Hiya Tony - the original plumbers couldn't access the pipework directly above the boiler as the bath is in the way - they had to cut the flow and return which came out from the boiler just in from of the sink, then used push connectors to join them to the new plastic pipework.

 

[newcastle phill]

Well if its a 2 pipe system i fail to see how it can be just returning without providing any heat to rads.
As I asked earlier...Is part an old 1 pipe system.
Sounds like the flow to upstairs is coming back into the flow somewhere else and not the return lol

 

[Tonycane]

I had an install with a similar problem, was 22mm speedfit on the first floor, the first 22mm speedfit tee off the flow blocked. Found the speedfit pipe insert had come loose and completely blocked the flow causing the same issues you have. I cut the flow and return and put a speed fit loop in connected to one rad to prove the boiler was doing good it's job and then passed it back to the installer. Just something to consider.

 

[knightime]

lol - you're probably right with the flow thing Tony! What I can't understand is why it worked for one day (the day the original plumbers left), but why the next day it failed!

I also don't understand how the flow and return pipes that I can see on the boiler are both hot, but in the bathroom only the flow is hot, while the return is cold!!!

It could have been that waaay back it was a 1 pipe system - the plumbers removed a lot of redundant pipework - but the 2 pipes above the boiler have been there since we moved in - 16 years now - so I'm assuming it's a 2 pipe system. All seems very strange to me...:ack2:

 

[knightime]

Thanks again for that Tony - I'll certainly pass on your experience to the plumber before he turns up tomorrow!

 

[Tonycane]

Flow and return being hot is the heat building up in the boiler and creeping up the return abit because it has nowhere to go.

 

[knightime]

Ahhhh, so it's possible for the flow to affect the return directly on the boiler side i.e both pipes hot, if the flow has nowhere to go?

 

[Tonycane]

Normally overheats first but it will get warm. I bet the boiler modulates down then goes off because it's sensing the return temprature

 

[knightime]

That's the thing Tony - it doesn't - and it doesn't make any noise/shut off/show error codes - it just chugs away like everything's fine! And that return pipe directly connected is as hot as the flow pipe, but that doesn't reflect on the flow/return upstairs. Sorry to keep repeating myself but it's proper confusing me at the mo lol!

 

[Tonycane]

Jesus, if I was local I would pop in just to see this ball ache!

 

[knightime]

Lmao - wish you were too buddy!!!

 

[knightime]

The answer is there somewhere - will keep you posted once it's all sorted (soon I bleedin' 'ope!)

 

[Howsie]

I have Howsie - this is the 2nd plumber I'm on!

Yikes! Where abouts are you based?

 

[knightime]

I'm in Worthing Howsie!

 

[mfgs]

I am down in Worthing for a couple of days next week. If you haven't got it sorted and you want another opinion I could stop by and take a look for you.

 

[Masood]

What I can't understand is why it worked for one day (the day the original plumbers left), but why the next day it failed!

If a lump of sludge or other debris was dislodged during the work they did, it may not have worked itself into a position where it could block the circulation until some hours later...

 

[knightime]

Fantastic mfgs - will keep you posted - thanks!

 

[knightime]

Thanks Masood - could be right there!

 

[Howsie]

I have Howsie - this is the 2nd plumber I'm on!

Same applies. Get a new one and lock them in until it's fixed.

 

[knightime]

I hear ya! This is the same plumber who replaced the pump and removed the trap - he's a really nice guy and open to suggestions, but seems to be stumped with this problem. If he's not able to rectify it tomorrow I'm gonna let mfgs take a look at it!

 

[Tonycane]

Sorted?