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

 

[alumb05]

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.

Hi, yeah, it has its own manifold and pump and there are 8 ports on it (sorry if I'm not getting the terminology correct).

I put the central heating on alone yesterday and it worked better. It's still not amazing but most of the rads heated up.

Not sure if the pump is on the flow or return, sorry.

I've asked my heating engineer if he can come over again so I'll send him this thread to look at as he'll know better than me.

Is there a new pump that you could recommend? I'm happy to give it a try and take a risk that it might just be the design.

 

[alumb05]

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.

Also.. my old threads are not for this house as we didn't live here then. Had issues at the last house but I think that was a water pressure issue.

 

[alumb05]

I may be completely wrong here, but I had a problem, which was caused because the boiler did not run for long enough. Yesterday View attachment 363472
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, View attachment 363475 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. View attachment 363476 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.

Thanks, I think my issue is slightly different as the heating can be on for hours but it's not powerfull enough to heat the ufh, rads and hot water at the same time.

 

[Johntheo5]

Hi, yeah, it has its own manifold and pump and there are 8 ports on it (sorry if I'm not getting the terminology correct).

I put the central heating on alone yesterday and it worked better. It's still not amazing but most of the rads heated up.

Not sure if the pump is on the flow or return, sorry.

I've asked my heating engineer if he can come over again so I'll send him this thread to look at as he'll know better than me.

Is there a new pump that you could recommend? I'm happy to give it a try and take a risk that it might just be the design.

You might be taking a chance with another 6M pump, albeit one with a greater capacity but the DAB Evosta 3 (NOT the Evosta 2 as it doesn't display any data) is a good pump, but you can also get a 8M Evosta 3 and still run it at the lowest possible head and only use the 8M if necessary, might be the prudent option but will cost a few more £. The Evosta 3 shows the flowrate and pump power, very useful.
THe 8M, I think, is 180MM between centres, the 6M is 130MM so a small pipe mod required.

 

[Madrab]

Could it be a lazy pump, yes.

As suggested earlier, system design tends to be the biggest culprit when it comes to slow heat up times, especially over more extended runs. Are you aware of how the system is setup with back bone pipe sizes, branch pipe sizes etc and how it's all run out to the rads and lengths of runs etc?

Ideally the backbone would be centralised within the property and the branch pipework out to the rads as equal in length as possible. Is there any microbore in the system?

What is the system load with rads and UFH combined against the boiler capacity?

BTW, the pump is on the flow towards the 2 ports.

 

[alumb05]

Could it be a lazy pump, yes.

As suggested earlier, system design tends to be the biggest culprit when it comes to slow heat up times, especially over more extended runs. Are you aware of how the system is setup with back bone pipe sizes, branch pipe sizes etc and how it's all run out to the rads and lengths of runs etc?

Ideally the backbone would be centralised within the property and the branch pipework out to the rads as equal in length as possible. Is there any microbore in the system?

What is the system load with rads and UFH combined against the boiler capacity?

BTW, the pump is on the flow towards the 2 ports.

Sorry, I'm not sure about how it is all setup fully as it was done before I bought the house.

The rads will work but not amazingly but I'd accept that if I could just get everything to work at once. It seems like it's a choice between the ufh or the rads or the hot water tank!

My heating guy has booked me in so I'll show him this as he'll understand it all better than me. Got to wait a couple of weeks though unfortunately.

Thanks everyone for the advice, appreciated

 

[Madrab]

It seems like it's a choice between the ufh or the rads or the hot water tank!

A CH system should be designed to ensure it is capable to do deliver everything that the system demands, if it can't then the design needs to be altered so it can. It's not a case of, ah well, I just need to live with a sub standard system. You do need a good resource though that is experienced with system design that can pick the system apart, highlight the areas that needs to be changed and report that back for decisions to be made.