Cold radiator

[jtheobald]

Here goes, I know I'm sure I'm not the first to ask this question.

Our CH boiler is approx 15 years old, although we have several radiators which are older. The house has a total of 6 radiators on a Potterton boiler and is the system is vented. To get heat in the house I have to turn the thermostat to maximum and also the boiler to maximum! However, whilst 5 radiators are hot the 6 is almost cold. There does seem to be hot water getting to the radiator as one of the feed pipes is hot; the other is cold! The radiator which is cold is downstairs but not the last radiator on the system (as far as I know). The valves are non-TRV.

I have replaced the pump, cleaned out the feeder tank (adding x800) which was heavy with mould and taken the suspect radiator off the wall and flushed it with a hose - nothing seems to make a difference.

I have read conflicting views about powerflushing. I intend on replacing the radiator which is cold but don't think this will improve the performance of the entire system. I can do without wasting money at the moment but will do whatever it takes as we're freezing. Can anybody advise me please?

Also, how much should I look to pay for powerflushing in Kent. I thought about doing it myself but it looks quite demanding.

Update, I have just checked the expansions take and again it has sludge in the top! Also, the bleed pipe in the airing cupboard also has air in it! I know it's not quite high enough so needs to be extended into the loft.

Thanks.

 

[Bahco]

//www.diynot.com/forums/viewtopic.php?p=1198051#1198051

Read above and maybe try the "bucket test " too.

 

[jtheobald]

Thanks Bahco,

I'll give the bucket test a go tomorrow. One other thing niggling me is my pump (Grundfos) is upset down. I have noticed the instructions say it shouldnt be upside down. However, the arrrow stating the flow is directed towards the motorised valve which I believe is correct?

I should have mentioned the rad has no air in it, just cold water.

Thanks.

 

[jtheobald]

After knocking out one new pump and a timer I now under the impression its a blockage. At least above the pump. I managed to move some crude and the pump's working again (still have the cold radiator though!).

The CH system has been running a few hours and I've just noticed that water is pouring out into the FE tank via the Expansion pipe! If I turn off the pump the water stops. Could this possibly down a blockage in the return to the pump, hence the water takes the easier route to the tank?

Hope this makes sense. All help gratefully received.

 

[seco services]

more likely a blockage around the vent/feed pipe where it joins the system pipework.

block like this useally needs cutting out and replacing.

 

[jtheobald]

I think that's what I mean and it makes sense.

Thanks for replying so quickly.

 

[jtheobald]

Would a powerflush remove this blockage?

 

[seco services]

run a magnet around the area i said see if it sticks to the pipework.

 

[jtheobald]

yep you're right its blocked! Thanks again.