Still not getting hot radiators

[dominoman]

After trying many things I still am not getting hot radiators.

The boiler is actually only working a small percentage of the time. I noticed the water returning to the boiler is very hot. Pipe almost too hot to touch. But other return pipes that I can easily get to under the house are only lukewarm. Same with the return pipes from my radiators.

How can this be? And what would you recommend I do next? Teaching all the pipework will be very difficult as a lot of it is under small crawlspaces that are not accessible without lifting the floor.

Thanks
Mike

 

[picasso]

I would recommend giving us a bit more info like boiler make/model do you have a hot water cylinder, bypass valve any where, has this suddenly happened or over a few months ect ect .

 

[dominoman]

Its always been like this since I moved in six months ago. I don't know if it ever worked better.

Since moving in I have fitted a magnetic filter and stained the system. I've also used sentinel sludge remover, which has been in for four weeks now but didn't have much effect.

Its an unvented system. Potterton suprima boiler in the basement, with a hot water tank upstairs, and a pump and diverter valve next to the cylinder.

 

[Agile]

You don't seem to have bothered to get the system services and checked when you moved in as most would do.

Instead you have spent six months knowing that you have problems and wait until cold weather when most engineers are very busy.

It seems to me that you need an engineer to diagnose the problem.

Tony

 

[StudWall]

Do your radiators have trvs? If so they may be turned down / off or be sticking closed

 

[jackthom]

If the radiators are generally cold and water on the return to the boiler is hot there's something acting as a bypass. Do any of the radiators get very hot?

 

[dominoman]

If the radiators are generally cold and water on the return to the boiler is hot there's something acting as a bypass. Do any of the radiators get very hot?

Yes three of the upstairs radiators get hot. But all of the downstairs ones only get lukewarm

 

[dominoman]

You don't seem to have bothered to get the system services and checked when you moved in as most would do.

Instead you have spent six months knowing that you have problems and wait until cold weather when most engineers are very busy.

It seems to me that you need an engineer to diagnose the problem.

Tony

Not at all. Before moving in I had a full survey. However the market was crazy at the time and I had to accept the house with all its problems or lose it. Not great, but hey ho.

I have spent the last six months fixing the urgent problems, working every night until midnight and all weekend.

I am simply asking for advice on one point.

 

[jackthom]

Yes three of the upstairs radiators get hot. But all of the downstairs ones only get lukewarm

I've a feeling we've been through this before but I can't remember the outcome. Can you say where the boiler/pump are located, maybe they're nearer to the radiators getting hot?

I would close off all the radiators that are getting nice and hot to see what the effect is on the others. Also check if the boiler return is still getting hot in this situation.
If the boiler return is cool AND the boiler starts cycling, there's a serious flow problem through the downstairs pipework. Could be sludge or the pump not too well.

 

[twgas]

The three threads you have running about your rads not working all point to a lack of circulation. A couple of possible remedies are, check/replace the pump, it might be full of system dirt! Ensure there is water in system, seems obvious but often overlooked! Check for restrictions in pipework, I'd start at inlet of pump and work back toward boiler.

 

[jackthom]

I can't remember all the history of this story but I think if it was me I might be buying a shiny new Grundfos pump and hoping it would at least help fix this.

 

[dominoman]

Thanks all.

I'd held off on replacing the pump as I've been working through other options first. I spent half a day today draining down the system after putting in gunk remover a few days ago.

Am about to do a second dose of that and then will replace the pump next week and see if that helps.

Thanks

 

[St0rmer66]

Sometimes all the chemicals in the world will not remove a blockage that simply cutting it out and cleaning with a long screwdriver would!

 

[bobby spray]

You may want to consider if you have a bypass hidden under the floorboards somewhere!

 

[dominoman]

You may want to consider if you have a bypass hidden under the floorboards somewhere!

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.