Will turning radiators on/off affect balancing and consequently return flow?

spinningsheep

Hi all, our boiler is due a service in the next few weeks, and I have asked the RGI to balance the system again when he comes, as some radiators are not heating up as fast they should, and I am only getting a 10 degree flow and return differential. We currently have the radiators in the 2 spare rooms set to 1 or frost as they are seldom used, if the system is balanced to allow a 70/50 flow & return, will us turning those radiators up or even off, affect the balancing in the future? Cheers

oldskoo1

Yes, you need to open all radiators to max, all TRV's to max. This is the key, you don't balance with TRV's set low.

It is possible to balance yourself, it's a lengthy exercise but its possible even by touch.

Standard procedure, go round all radiators in order of how they heat up, adjust the lockshield until you get the required temperature difference.

Once done just re-adjust your TRV's. You will still have the correct flow through each rad. Just some of the TRV's will shut down and the water will be directed elsewhere.

If you have TRV's on all but the wall stat rad you may find your boiler cycles more until temp is reached, unless your boiler modulates the gas input and modulates the pump speed.

It's also best to balance on pump speed 2 unless you have a very big system and need pump speed 3 (unlikely if correct pump rating is fitted).

If you balance the system with these radiators off and then you suddenly start using them again, the lockshfields might not be correctly balanced for the system and it will all need re-adjusting.

I wouldn't fuss too much over it, it isn't an exact science but simple tweaking yourself can produce much better results.

Andy_WSM

Another trick is to turn down the boiler temperature slightly. The important thing for condensing boiler to condense (therefore run most efficiently) is for the water to return to it at less than 55C. If you're only getting a 10C differential, turn the boiler flow down to 65C.

Yes, it will take very slightly longer to reach temp in the rooms, but the boiler will run more efficiently getting there.

spinningsheep

Thanks guys, yes I am running the boiler on 65 now so I get approx 54 return, I was hoping by getting the system effectively balanced I can obtain a faster warm up time at 70/75 but still achieve a 55 return.