O/T Bleedin' radiators!

[MartinH]

Hi Folks,

 

Can anyone advise me what to try next with this problem?...

 

Some of the radiators in my house are very hot, some are warm near the top but cold at the bottom and some are freezing cold all over. It is a two storey house with a standard boiler (not combi).

 

I have gone around all the radiators and bled them although no air came out of any of them at all. All had water flow out when I opened the bleed valves.

 

There doesn't seem to be any pattern to it either. Some physically close to the boiler are cold and some further away are hot (although I don't know the pipe routes.)

 

It was the same last year and I don't feel the cold that much but SWMBO's patience has now run out and as she feels the cold a lot more - they NEED sorting!!

 

There is another problem with the system, although I don't think this is the cause of the first problem. If the heating is switched off at the electronic controller/timer and the hot water is on - the radiators still come on. This has only started happening in the last few weeks. I think this might be something to do with a control valve of some kind (3-way?) - which went wrong also in our last house.

 

I will have to call in a plumber to do the valve I guess but that is not as urgent as the freezing radiators. Any ideas what to do next?

 

Cheers,

 

Martin

 

Duratec R300 SV Build Pics

[Stationary M25 Traveller]

If any radiators are cold at the bottom, sounds like they are sludged up. Have you ever drained the system and refilled it with an additive like Fernox ?

 

There has been another thread recently about motorised 3-way valves, and the ease of changing the synchronous motor which can be bought for around £14 (?) from Screwfix. This is a dry job, as it is external to the wet bits !!

 

 

[Martin J]

It sounds like you might have a bit of a sludge problem with your heating system ☹️& may be in need of a full powerflush.

Rads that are not working (unless it's a trv stuck in the off position) or that are cold at the bottom are probably sludged.

If I powerflush a system it would include cutting out & replacing any "H" pipework in the airing cupboard by the pump as this can be the start of a lot of problems & fit a new pump.

Is your system pumping over ie hot water in the header tank? As over time this will make the water very mucky due to increased corrosion.

re rads staying hot when on hw only, you are correct that the 3 port valve has probably had it, again sludgy water isn't kind to motorized valves.

[MartinH]

Thanks guys. Have never heard of Fernox - I will Google that and see what thats all about. The water coming out of the bleed valves is indeed brown and yucky. Maybe it does need draining... Have never heard of power- flushing but it sounds like a good idea if sludge is settling at the bottom of the rads. How much would I expect to pay for a job like that? What is involved? Can it all be done from the airing cupboard where the valves are or do we have to get floor boards up all over the place etc?

 

Cheers,

 

Martin

 

 

Duratec R300 SV Build Pics

[virden]

Martin, have you checked your pump to see if it is operating correctly?

How much water did you take out of each radiator. Air does not always come out as soon as the bleed valve is open. Try taking out about half a pint from each. i fthe water flows freely from each then this will also confirm that your feed pipes are working correctly. Are the valves on the radiators thermostatic? If so they do have a tendency to stick, a gentle dunt should help. Failing any of that working, then it is time to call a heating engineer. Not a plumber.

Good luck

[MartinH]

Not sure how to check the pump - or even where it is! I only took a few seconds worth out of each radiator - not as much as half a pint. In my last house we have a problem with air getting into the system and I had to bleed the rads every couple of weeks. Then I would always get air out first so I assumed this time that was not the problem as no air came out at all.

 

About half of the valves are thermostatic but quite new. All set to full on. I have turned them up and down a bit in case anything needed loosening.

 

Time to call in the pros I reckon

 

Duratec R300 SV Build Pics

[Martin J]

Done properly power flushing can transform a sludged system No need to lift floors, generally connected to pipework in the airing cupboard. The trick is to be thorough, we (British Gas) allow a full day & more on larger systems. Fit a magnetic sludge filter such as a magnaclean to the system will prevent any future problems & add a good corrosion inhibitor such as fernox.

SM25's suggestion of adding a cleaner & just allowing it to circulate around the system can work on lightly sludged systems but you only useing the flow from the heating pump whereas the powerflush machine hasa large powerful pump on top of it's tank.

Not cheap I'm afraid ☹️ We charge from about £500 but a good independant installer may well be less

[Cookie Monster]

Hi Martin

Worth talking to the Hatter? He is supposed to be a specialist on these matters when not building big output cars

I have a mate who is a plumber in Hazlemere who might be worth a shout if you don't know anybody/ have a more local recommendation?

 

Phil

[MartinH]

Hi Phil,

Yes - I mailed Carl a while ago. No reply yet. He's probably upside down under the Yob wondering why his fancy French gearbox doesn't want to mate with his new carbon prop-shaft!! 😬

 

I'll give you another shout for your contact if he's too busy to look at it.

 

Cheers

 

Martin

 

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[Cookie Monster]

Martin

 

I had heard he is handy with an angle grinder on fancy french metal 😳

 

Think Carl's mobile is in LF but I have it if you need it, just BM me.

Let me know re. Stuart(my mate) if it doesn't pan out.

 

Phil

 

Edited by - Cookie Monster on 14 Nov 2010 18:48:33

[Racing Snake]

Martin give me a call tomorrow

I can sort it for you i have a French power flusher 😬

 

---

Mad Hatter The Dura Mentalist 😬 Carl @ Penn 7's Caution - May Contain Nuts !

[Stationary M25 Traveller]

A bidet ? 😬

 

 

[PAC]

Martin, just an obvious point, have you tried opening the balance valves (Opposite end to TRV's) on the cold rads?

Your pump will have an isolation valve either side of it, you can remove the motor and impeller assembly -usually by removing four Allen bolts, without getting wet. If you have sludge it will probably be fouling the pump impeller, and need scraping out.

P

[MartinH]

Hi PAC,

 

Yes, I have opened up those valves as much as I could on the very cold ones - although mostly (if not all) they were fully open I think. I also took the plastic component off the top of the thermo valves and clouted the valve underneath a few times with a rubber mallet to see if that made any difference. The little plunger thing in the middle only seems to have a few milli of travel - is that right?

 

In any case - I have called in the Hatter now and hopefully he can get me sorted.

 

Cheers all for the suggestions.

 

Martin

 

Duratec R300 SV Build Pics

[peterg]

FWIW it's not opening the valves on the cold ones you need to do, it's adjusting (ie closing a bit) the valves on the ones that get hot so that the pressure is balanced...

 

we had this in our current house (no sludging found) and it turned out the previous tenants had mistakenly opend all the valves up fully so there wasn't enough back pressure to allow the radiators to heat up as the water flowed too quickly