Balancing central heating system

[pippo]

Hi folks,

I have been researchimg this on the tinternet and the axcellent guid in the FAQ,s. However, I just want to check if I can balance my system in the same way. My system (which I will have completed tomorrow) has a T piece shortly after the boiler, the flow/return going left will feed the kitchen rad and 2 rads upstairs, the flow/return going right will feed the downstairs 4 rads. My question is, do I balance it as if it is 2 systems, i.e. start with the kitchen rad then the 2 upstairs, then balance the rads in order for the downstairs 4. Or is that over complicating things? Also, I am using barrier pipe, will the readouts on the thermometers be accurate if places on the barrier pipe tails?

Thanks

Pippo

 

[possum_jenkins]

You are over complicating! The system should be treated as one. You will get a false reading from barrier pipe. Assuming you are balancing a system with a condensing boiler, you could clap on your thermos to the copper flow and returns into the boiler and balance until you get a 20 degree differential.

 

[pippo]

possum_jenkins,

It is a combi system. So I just need a difference of 11-12 deg C (20f) at the boiler flow/return and the system is balanced? Would i get a good reading off the body of the lockshield/trv ?

thanks

pippo

 

[D_Hailsham]

The temperature differential depends on what the boiler mfr suggests.

What make/model is you boiler?

Setting the temp differential at the boiler is done by adjusting the pump speed. It is just the first stage in balancing. You still need to adjust the lockshield valve on each rad to obtain the correct drop across each rad.

1. Open both valves on all rads. If you have TRVs remove the tops
2. Adjust the pump speed to give the recommended temp drop at the boiler
3. Adjust the bypass valve, if fitted, according to boiler/valve mfr instructions.
4. Close all lockshield valves
5. Starting with the rad nearest the boiler, open lockshield a quarter of a turn and check temp drop across the rad. If the drop is too small, shut the lockshield a fraction and vice versa. There is a fair time delay before the change registers.
6. Move to the nearest rad in the next branch and repeat 5
7.Adjust each rad, always moving away from the boiler.
When you have done all rads, go back to the beginning and check each rad, tweaking where necessary.

Notes:
1. A radiator with a temp diff of 20°C (75°/55°) will give out about 15% less heat than one with an 11°C diff (75°/64°). In normal circumstances this will not be noticed as radiators are invariably oversized and you only need the full output when the outside temperature is below 0°C.

2. The greater the differential, the slower the pump runs, which saves electricity.

 

[pippo]

D_Hailsham

The boiler is a worcester 28i junior, will this adjust the pump speed automatically?

pippo

 

[D_Hailsham]

The boiler is a worcester 28i junior, will this adjust the pump speed automatically?

If there is no means provided for adjusting the speed, it must be controlled automatically. Just measure the flow and return temps at the boiler with all rad valves open and use that as your guide for setting the drop across the rads. This boiler also has an internal bypass, so you don't need to worry about that either.

 

[kinhell]

What sort of thermometer are you using to check the difference? I need to balance ours at home.

 

[D_Hailsham]

What sort of thermometer are you using to check the difference? I need to balance ours at home.

Mechanical ones which clip on the pipes are very slow reacting to changes. I suggest you get an infra red one from Maplin; they cost about £20.