2 cold rads, ideas exhausted

[Jane17]

We have 1 luke warm and one cold rad in hall and living room. It started last year and have put up with it but trying to solve. Put desludger into system for a week plus and then drained and flushed system thoroughly. Refilled and not solved.

Drained again, took radiators off, flushed thoroughly lots black stuff came out even though water had run clear on draining whole system. Put back, no change. Shut down all radiators but these 2 and still no change.

Can feel hot water in pipe to hall rad but not as hot as other rads. Cold rad pipe entry feels luke warm. Advised to change pump. Did so and this had no effect either. When we drained system one of the times we did it out of one of the bad radiators and it drew hot water through both rads.

The pin on the trvs are going up and down fine. Boiler gas Stelrad/Ideal Mexico. Nothing changed before it started happening. We've done a fair bit of plumbing before but are so out of ideas, help!!

 

[Bahco]

Read this

 

[Jane17]

Thanks, but yeh I've read this. The only thing on this list which we haven't done or checked is the zone valve/3port valve not opening, but surely if the inlet pipe to both rads is hot then this must be working??

 

[Bahco]

Balancing / sludge problem!

 

[Jane17]

Ok cheers bahco but we've drained and flushed the system 3 or 4 times. Is there a better way of doing this to be sure that the pipes are clear?

Also do you think that there is any chance that either of these radiators might be corroded enough to cause this, even though we've removed them, flushed them and water seems to flow through them well enough?

 

[Bahco]

Have you took the rad off and then opened each valve up (one at a time) and allowed water through into a bucket. Try it with all other rads off.

If there is no blockage then the water will HAVE to flow into the bucket.

Let us know how you get on.

 

[Jane17]

That sounds a good idea, not sure if we've tried that yet. Will have to check with the other half. At the moment we'll try anything as we're not convinced that a plumber will know much better and will charge us a fortune probably for going through what we've done already. We 'll have a go at that and get back to you sometime. Probably have to wait till traditional DIY day next Sunday. Hope you're still about next week at this time! Thanks VERY much for all your help. Jane

 

[Agile]

So what desludger did you use and at what dosage?

Tony

 

[Jane17]

Hi Tony Sorry that you took umbridge to my comment. It was not meant in the way you took it. I was trying to be concise and not give too much detail as we had tried an awful lot of things, more than I wrote down. When living in our old house we put in our own complete water and central heating system from scratch. My hubby Richard designed the system and I (a woman, god forbid), plumbed it all. We moved after 10 years in the property without any problems so we felt we had a fair bit of experience to tackle this problem, but it has foxed us and incidentally some of the local plumbers who we asked for advice, one of which suggested replacing the pump which we did to no avail. So it was not meant to be a dig at plumbers!!

 

[USEFULDIBDOB]

are you on small bore 22mm flow and returns, 15 mm to rads or mico bore 10 mm to rads, have you had any work done that might have flattened a pipe ?

 

[Jane17]

Hi, we have 10mm microbore. It is interesting you suggest this as when we arrived at the house 8 years ago, the system had been put in by the resident's son, a young apprentice plumber. He cut corners by putting radiators in silly places, but also the place has a concrete floor and he cut into that to sink the pipes and cemented over the top. This cement had cracked and we had to redo it, but the pipes run quite close to the surface and across rooms and doorways where there is constant movement. In one of my wilder moments of troubleshooting i wondered whether we'd squashed a pipe, but the pipe running into the hall rad which is lukewarm is quite hot, though not as hot as all the others; and the pipe running into the cold rad in the living room, further from the boiler is also warm so would that still be possible. Do you think it could be slightly squashed enough to reduce flow? I guess the bucket test would show the speed of flow, but then as amateurs we probably wouldn't know how fast it should be anyway!

 

[Jane17]

This is for Tony, will get back to you later with what desludger it was and how much as Richard did that and isn't home till late.

I can't believe people are interested in our problem! Thanks

 

[USEFULDIBDOB]

its hard to say wiyh out looking at the lay out of the house, but it is posible a pipe or pips could be flatend or traped, one customer i went to, the 10 mm ran ran along the scirting board and she had flatend it with the hover in too of her rooms, it might be worth looking for damage

 

[Jane17]

It will be easier said than done! But we'll check, thanks.

 

[bengasman]

If you still get black out of the system, you need to stick the cleaner in again. I mostly use HYPERFLUSH for soft flushing, and have also had good result with fernox f3. If the problem persists, you may have to look at more drastic measures like powerflush or pressure flush using the mains if you got a proper pressure.