Balancing radiators

jollyanna

I had a new boiler (valiant) fitted 3 months ago on the warmfront scheme. The engineers were always so hurried and I knew they hadn't got the system properly balanced , it had been a tricky installation due to air blocks. They left with saying "any problems , give us a ring". We've had the heating on a couple of weeks and I decided to give it time to settle before calling them out but although upstairs seems fine, downstairs only one small rad heats up. we've been bleeding them when the system is off and some orangey water trickles out( probably the flush they gave it ). What else can I try before seeing if they will come back? We've had temp valves on all but one of the rads. We have 7 rads down and 6 up.

a&akay

Try turning off all the radiators at the non trv valve at the other end except for the one that doesn't have a trv, leave this on. See if your pump has 3 settings and turn it to the highest. You can usually hear it working harder ie providing more head. Turn on each rad downstairs in turn starting at the one nearest to the pump. Turn the trvs on each to the highest setting. This may force out any air into this rad because most of the pump's energy will be going through this one small circuit. Bleed it if this works then turn off the non trv valve and go to the next one.

Once and if they are all heating up you will need to balance the system by trial and error. The water will find the easiest route ie line of least resistance so you may need to turn the non trv valves closest to the pump more off than those furthest away eg upstairs.

Turn the pump down to the lowest setting that gives your rads good temperatures.

david29dpo

Agreed. With balancing, you are trying to make sure all the rads warm up at the same time. When you put the heating on from cold, walk round the house and feel the rads, if one gets hot quicker than the other, turn the LSV down slightly, this is the other end of the rad, not the TRV. Sooner or later all rads will heat up at the same time. You can use 2 thermometers on the feed and return of each rad instead.

escroooge

I read on the net somewhere a radiator is balanced when the difference in the input and output temperature is 20 degrees F.

http://www.diydata.com/projects/centralheating/balancing/radiator_balancing.php

ollyk

I think your original installers should have done this!

economiser

escroooge wrote: »

I read on the net somewhere a radiator is balanced when the difference in the input and output temperature is 20 degrees F.

!80F (82C) flow and 160F (71C) return used to be the design criteria for domestic heating systems. However for a condensing boiler to work at its maximum efficiency the return water should be 55-60C. This of course means that the radiators will be cooler and give off less heat.

Unfortunately much of the publicity for condensing boilers does not acknowledge this.

Canucklehead

economiser wrote: »

!80F (82C) flow and 160F (71C) return used to be the design criteria for domestic heating systems. However for a condensing boiler to work at its maximum efficiency the return water should be 55-60C. This of course means that the radiators will be cooler and give off less heat.

Unfortunately much of the publicity for condensing boilers does not acknowledge this.

Good evening: An excellent (though technically complex) read on condensing technology is available at http://www.viessmann.de/en/literature/Technical_Series.DepartmentDescription.35207.downloadlistitem.86633.FileRef.File.tmp/ts-condensing-technology.pdf though I suspect very few installers measure flow and return temperatures when commissioning a CH system.

HTH

Canucklehead

alanobrien

Correctly balancing a heating system is part of part of the comissioning process so your installers should have done this. In my experience they rarely do though. That said with zoning these days and the use of TRV's it is less of a problem than it used to be. You should get them back in to complete the job properly.

Canucklehead

Good evening: I suspect the system wasn't properly flushed i.e. with Sentinel or Fernox CH sludge remover followed by inhibitor...orange water doesn't sound very promising...is it possible that the orange colour is a result of rust? The installers haven't followed the manufacturer's installation/commissioning procedure. Did they fill in your Benchmark log book (a installation/service record provided by Vaillant as part of their installation booklet)? Too many CORGIs are in a hurry and cutting corners to get on to the next job :mad:

HTH

Canucklehead

economiser

Canucklehead wrote: »

Good evening: An excellent (though technically complex) read on condensing technology is available at http://www.viessmann.de/en/literature/Technical_Series.DepartmentDescription.35207.downloadlistitem.86633.FileRef.File.tmp/ts-condensing-technology.pdf though I suspect very few installers measure flow and return temperatures when commissioning a CH system.

HTH

Canucklehead

I understand the technicalities of condensing technology but realise that most people do not realise the implications of the requirements to make it work effectively. I absolutely agree that hardly any domestic systems are commissioned properly which is making a mockery of the supposed savings of condensing boilers.

Thank you very much for the link to Viessman, I hadn't seen this before. It looks a very useful and comprehensive dissertation.

jollyanna

My thanks to all for your helpful contributions. We've decided it's clearly not going to get sorted in a couple of hours, so we plan to spend the w/e tweeking it all after further reading.
Warmfront inspector has not yet been to sign it off, when/if he comes I'm not going to sign it off myself until the installers have had a chance to set it to rights i.e. if we can't make a very great improvement before then.