Cold radiators - totally flummoxed

dollydolittle_2

Hi all

We moved into our house (built in 1960s) earlier this year. We knew the boiler was not just G rated but X rated and needed replacing but we also discovered that a the radiators in the living room were cold at the bottom and only slightly warm at the top - we assumed sludge had collected there over the years. Some of the other radiators seemed to be hotter at the top than the bottom, but in the 2 living room radiators there was hardly any heat at all. The pipework is microbore.

So a couple of months ago we had a new combi boiler installed, the two radiators removed from the living room and replaced with one new double, and thermostatic valves fitted to most rads. We didn't power flush because of the microbore, but did put cleaner in (twice actually because the work took a couple of days) and I also had a magnaclean fitted. However, the brand new living room radiator still only produces a hint of warmth from the top.

What do I do next? The heating engineer said it could be pipework which will be difficult, expensive and messy to sort out or it could be air in the system and to wait and see if it sorts itself out. We have indeed been bleeding air from the rads upstairs, but it doesn't seem to make any difference to the living room rad. and I don't understand why there is air there anyway as it is now a closed system and they emptied and refilled at least three times while they did the work. And anyway, wouldn't air mean it would be cold at the top?

Can anyone help me understand what is going on? I'm gutted that we have spent so much money on this and still can't heat the living room at all and am really unsure what to do next.

Many thanks in advance

macman

Air getting in eventually rises to the highest point of the system, i.e. the upstairs rads.
Have they balanced the new rad properly?

dollydolittle_2

Thanks Macman

Well, they said they did, but if they had then wouldn't all the rads have been working properly when they left? Obviously they weren't and they knew that, and so advised me to wait six weeks to see if it settled down.

Can new air be getting in to a closed combi system? or is the air we are bleeding out still left over from before we had the work done?

Freddie_Snowbits

The first thing I would do is bleed the new radiators in the lounge.

http://uk.video.search.yahoo.com/search/video?p=Bleed+Radiators&fr=bt-portal&toggle=1&cop=&ei=UTF-8

You will have to turn on the heating to do so. There will be a hiss of air until water flows. Make sure the thermostatic valvle (waste of time in Freddie's opinion) is full on.

dollydolittle_2

Sorry, I should have been clearer, we've been bleeding all the radiators regularly, no air at all comes out of the downstairs rads, only water. We have been getting air out of the upstairs rads and a couple of them are quite noisy when the heating comes on.

I don't understand how there could be air underneath the water in the new rad. And when I say it is cold at the bottom, I mean cold all the way up until maybe the top couple of inches which are slightly warm. One pipe is hot and gets hot quickly after I turn the heating on. The other pipe (the one with the valve on) is cold.

(btw I had heard that about thermostatic valves, but was also told they are 'industry standard' now - it does seem that in reality they are either on or off, and it annoys me that the numbers are upside down! I didn't have them fitted to all the rads and won't bother doing the ones that don't have them in the future. But while we are exploring my experience: I am so glad we had the magnaclean fitted, you would not believe how much it collected in the first couple of weeks. One of those brilliant but simple ideas)

ariba10

Next time you put the heating on. Turn off the hottest radiators and see what happens.

If the cold ones warm up, it is probably a balancing problem.

dollydolittle_2

Thank you. Will do that tonight.

rosalie-lavender

We had a problem where one of our downstairs radiators stayed cold when the rest were hot. Our problem turned out to be the thermostatic valve was jammed and not allowing the hot water through. I don't think our radiator was hot at all though, but it might be worth investigating whether the valve is causing a problem.

dollydolittle_2

Didn't make any difference.

I paid them when they left after installing the boiler, but do you think I am justified in asking them to come back and have another go at sorting it out as part of the original job? Obviously, I wouldn't expect them to replace significant amounts of pipework without an additional payment, but what about a return 'diagnostic' visit?

And yes, lesson learned to always ask 'what if' when I employ people to do stuff like this, but we were so sure it was sludge at the beginning.

Cardew

As suggested above, have you checked the TRVs; the 'plunger' can stick.

Unscrew the knurled nut and take off the top of the TRV(don't worry no water will escape!) and there is a thin metal plunger which can be 'exercised' (moved up and down) it has a very strong spring. They can stick in the 'down' position - a couple of mine do this regularly.

withabix

Did they replace the circulation pump? Does it make any sound? Itcould be blocked/jammed with sludge or not working at all.