Radiators not heating

[alumb05]

Hi, I've had three different heating engineers out to look at my radiators as they just don't heat up as you'd hope/expect! They still don't work great so I'm wondering if I got a new very powerful pump, could that help push the hot water around better?

We have a load of rads and also a two zone underfloor heating system. If everything is on together then nothing seems to work and the hot water tank also doesn't heat up! My heating engineers have been out to try and balance things more than once but it's not fixed the issue. I think that the rads are maybe not piped up too well in a good way to allow the flow to easily get around but just wondering if a bigger, newer pump might improve stuff rather than re piping the whole house! If I just have the radiators on for 5 hours non stop then they will eventually heat up but obviously that's not a great situation! I'm just hoping a new bigger pump might just force the flow around better and also mean that the hot water will heat up if it's on at the same time as the rads and ufh.

 

[cross thread]

Sounds like system design
How many rads ? and good photos of your boiler and piping arrangement would help us to give some ideas.

 

[alumb05]

Hi, 11 rads and a two zone ufh system. I think it's definitely a bad design as it's an old house and the rads have been changed over the years and removed with the introduction of the ufh to then remove extra rads. It's a pretty big house so there's quite a distance for the water to flow around.

I'll get some pics shortly.

Thanks for the quick response

 

[alumb05]

 

[alumb05]

Sounds like system design
How many rads ? and good photos of your boiler and piping arrangement would help us to give some ideas.

Any other thoughts after seeing the pics? My hive app just shows that the UFH and Rads are pretty much on all the time trying to get the rooms to 18 degrees. The Rads are not even working it seems as the UFH is taking everything. I think everything in the boiler cupboard is new except the boiler and pump. My hope is that whilst a new more powerful pump might not completely resolve the issue, it might just force the hot water around everything better????

 

[Johntheo5]

Does the UFH have its own manifold pump & TMV, how many loops, what temperature is it running at?. What is the boiler flow temp?.
If you run the CH on its own, any improvementn̈? Is the pump on the flow or boiler return.
While those Selectric pumps were very long lived, the 70W wouldnt be that powerful, you could isolate it, remove the pump head and ensure/cleanout the impeller vanes with a tiewrap. Will have a look at pumpcurves later.
Thats a vetern pump....PC1107, built in week 7 2011.

Looking at one of your old threads. you have had this problem since 2009.

 

[ericmark]

I may be completely wrong here, but I had a problem, which was caused because the boiler did not run for long enough. Yesterday

The 8 am burn was long enough, as was the one when raised temperature to 19ºC, but the other burns would only heat a couple of radiators fully, as simply not running long enough to reach all the radiators.

In real terms the display shown is a back-up, I also have a second thermostat that now keeps the boiler running for longer, the second thermostat only shows room temperature and temperature settings, not when it run the boiler, but real control of the room is with the TRV heads. which also report how they have done, which seems reasonably good, and we were comfortable in that room yesterday, but it does not matter what the TRV does if boiler not running, or what the boiler does if the TRV is closed.

Ideal is to have the TRV control the boiler, so boiler runs when required, but as yet not done that, idea is as TRV's close, it will force water through those still open, so there may be a delay with some rooms heating, but they all will heat up, but of course only if the boiler is running.

I see you use Hive, I believe Hive will only accept a demand for heat, if the wall thermostat is below 22ºC so having the room with wall type thermostat set too high could stop other rooms heating up.

 

[cross thread]

From the photos I would be looking at reconfiguring the boiler cupboard with either low loss header or close couple tee set up , only my opinion