Still not getting hot radiators

[StudWall]

First thing I would do would be to isolate them and drain them then flush them.

I had the same problem when I moved in and by flushing (pressure washer in one end, other end down the drain) about 20 minutes for each radiator was black sludgey water. After that they were great.

Then fit a magnetic filter (I got boilermag from toolstation) should prevent that problem reoccurring

 

[jackthom]

Yes - I must have one somewhere. Even with all the "hot" radiators closed I can't get any decent circulation to the lukewarm ones. Unfortunately I just can't find the bypass wherever it is.

Next step is to replace the pump. Next weekend's job. Maybe that will sort it.

The big question is does hot water begin to reappear at the boiler return even when all the radiators are still barely warm.

 

[dominoman]

Yes - I must have one somewhere. Even with all the "hot" radiators closed I can't get any decent circulation to the lukewarm ones. Unfortunately I just can't find the bypass wherever it is.

Next step is to replace the pump. Next weekend's job. Maybe that will sort it.

The big question is does hot water begin to reappear at the boiler return even when all the radiators are still barely warm.

Yes - even with radiators barely warm the return flow to the boiler is hot... That means there is a bypass somewhere I presume? Th trouble is finding it.

What is the point of a bypass? Wouldn't it always lead to poor circulation in the rest of the system, as water will take the easy path?

 

[StudWall]

The bypass is designed to open when the pressure reaches a certain level to protect the pump when the trvs shut off.

Have you thought if the diverter is stuck open to rads and water tank?

 

[dominoman]

The bypass is designed to open when the pressure reaches a certain level to protect the pump when the trvs shut off.

Have you thought if the diverter is stuck open to rads and water tank?

That's definitely possible! So if the diverter wasn't working the water could flow to the hot water tank and back to the return - which would avoid it being pushed through the radiator?

My diverter has a switch on the side that pushes upwards and can be manually locked into position on a small notch. If i move that to the top should it force it to go only to the Central heating?

 

[StudWall]

Not sure exactly as I'm no expert it was just a theory, easy to check by turning heating on and water off, go to the tank and feel if water is flowing through the feed & return pipes, also if the how water has been off for a while they should be cold and get warm if that is the case

 

[bobby spray]

Sounds exactly the same as my systen, I went through all the options,

powerflush
new pump
bigger pump
TF1 filter

I still have lazy flow to some rads and I assume that there is a bypass hidden under the floorboards somewhere. Judging by the age of my system it's mroe likely to be a manual tap set up rather than an autobypass. I don't fancy pulling up the parquet floor to find out though!

 

[dominoman]

Sounds exactly the same as my systen, I went through all the options,

powerflush
new pump
bigger pump
TF1 filter

I still have lazy flow to some rads and I assume that there is a bypass hidden under the floorboards somewhere. Judging by the age of my system it's mroe likely to be a manual tap set up rather than an autobypass. I don't fancy pulling up the parquet floor to find out though!

You've given me some new ideas. There are several red turny tap things near my hot water cylinder. Perhaps one of those is bypassing between the flow and return.

I'm going to search again tonight.

What did you do in the end to get warmer radiators?

 

[dominoman]

I wasn't able to find a bypass unfortunately. But there must be one somewhere because downstairs radiators are still cold even with the hot ones upstairs turned off.

Using some diagrams I found on this site I've tried to label the pipes I can see. Would someone be able to tell me if this looks right?

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• dominoman
• 8 Dec 2014
• 1

The pump is at the top right of the photo and then goes to a divertor valve. In the picture the side of the valve towards the tank is hot water and the other is CH. I think the pipe at the bottom must be the return to the boiler, as it gets slightly less hot than the other pipe

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• dominoman
• 8 Dec 2014
• 1

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• dominoman
• 8 Dec 2014
• 1

In the diagram the one that I marked cold water feed (if it is?), that pipe gets very hot as soon as the pump stops. If I restart the CH or HW the pipe immediately gets cold again, so cold water is coming down it.

I also noticed today - and I don't know if this is connected - that when I turn off the system the tank overflows. It seems fine while it is running but overflows as soon as the pump stops.

Anyone that can help at all I would really appreciate it. I have no money to get a plumber in - and I feel at my wits end with this system now after so many weeks of trying.

 

[StudWall]

Looks right to me, where do those grey and white pipes go to / from?

 

[dominoman]

Looks right to me, where do those grey and white pipes go to / from?

They go down through the floor into a space that I can't get to - so I don't know where.

They also go upwards into what I presume is the radiator in the loft.

Is it normal that hot water rushes up the cold water pipe from the air separator when the pump stops? I'm pretty sure it is pumping over because the pump is set to maximum.

Should I be getting a powerflush now? I wanted to avoid it as I don't have the money but now I am out of ideas.

 

[StudWall]

Possibly down to a basement or void to prevent damp.

Not sure of the answer to your question as I've never used one.

The fact that some radiators are getting hot indicates that the pump is likely ok imo.

If your downstairs radiators are cold it does sound to me like a sludge problem, you'd be amazed how much crap appears so quickly. Have you tried turning the hot radiators off and turning the pump up to see if it can get it moving?

 

[Dan Robinson]

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• dominoman
• 8 Dec 2014
• 1

I think I have been a little bit sick in my mouth. . Fook me.

 

[dominoman]

Possibly down to a basement or void to prevent damp.

Not sure of the answer to your question as I've never used one.

The fact that some radiators are getting hot indicates that the pump is likely ok imo.

If your downstairs radiators are cold it does sound to me like a sludge problem, you'd be amazed how much crap appears so quickly. Have you tried turning the hot radiators off and turning the pump up to see if it can get it moving?

Yes I've tried turning off the hot radiators and with the pump on maximum it still doesn't get the downstairs ones warm. Someone suggested there must be a bypass somewhere - but I just don't know where to look.

Should I just bite the bullet and get a powerflush?

 

[StudWall]

There may no be a bypass at all, what makes you think they would fit one, and if they did, why would it be somewhere you can't access, if there was one I'd bet 99% it'd be in that cupboard.

If you've got a few hundred to burn go for it. I got a pressure washer for £30 and an assistant paid in tea and bacon sandwices, it took us half a day or so to do 6 rads and the result was incredible