General Commissioning

[Heatpumpjoe]

Hi All, I'm new to this forum and to be fair am not a plumbing or gas engineer! instead I'm a refrigeration/air conditioning engineer who is generally thinking as an engineers does so have a few questions regarding commissioning that you guys hopefully can answer for me? I have also started into the world of domestic heating/hot water for domestic use due to the influx of air source heat pumps that are coming into the market. It does make me laugh that because the refrigeration process is used to heat water and lots of people are having them installed we are all of suddenly expected to be able to go into customers homes in the domestic market and fault find on wet systems. Anyway enough of the ranting, can you please comment on the questions below regarding my home system? Basically what is the best flow temperature which should beset at the boiler? I have clamp thermocouple so I can easy view this. As youknow most boilers only have a scale hotter to colder. How do you balance radiators for rads with no thermostatsand rads with thermostats? what TD should I be looking for across the radiator? In the terms of energy consumption I would think this has adetrimental effect on my gas usage. My boiler is a Baxi Combi 105 HE. I have a Honeywell CM67 timer/stat so am happy with thesetup to correct occupation times and set points required. Any help would be great.:smile5:

 

[Dotty]

Welcome to the UKPF Joe. We get asked the balancing thing all the time. Try and get about 70degC flow temp.

Then follow this how to guide. FoC


How To Balance Radiators
Tool List:

Radiator-bleeding key
Lockshield valve adjuster or adjustable spanner
Screwdriver
Digital thermometer or multimeter with thermometer function



1. Make sure all the radiators have been bled. Turn off the central heating and allow the radiators to cool.

2. Familiarise yourself with the valves. The lockshield will usually have a push-on cap or one that is secured with a screw through the top. Remove it.

3. Older models will have a wheelhead valve on the other side — used to turn the radiator on/off.

4. Newer radiators will have a thermostatic valve instead of a wheelhead valve.

5. Open up the valves on all the radiators in the house by turning them anti-clockwise.Wheelhead and thermostatic valves can be turned easily by hand, but the lockshield will need a plastic adjuster to open it up. These come with new lockshield valves. A spanner will also do the job.

6. Turn the central heating back on and note down the order the radiators heat up. Those nearest the boiler normally get hot first. If you’ve got a lot of radiators, get assistance. Turn the heating off and wait while the radiators cool down.

7. When the radiators are cool, switch the heating back on and go to the first radiator on your list. Turn the lockshield valve clockwise until it is closed and then open it by a quarter of a turn. Once the radiator has warmed up, take a temperature reading at the pipework leading to one of the valves.

8. Now take a temperature reading at the pipework leading to the other valve and open the lockshield valve gradually until there’s a 12°C difference between now and the reading you took in step 7 (allow a couple of minutes after each adjustment for the temperature to change). The temperature figures indicated in the last step and this one are relevant to the radiator shown – don’t take them as any kind of optimum figure – it’s the 12°C difference in temperature at the valves that counts. Next, check the rest of the radiators in the system following the order in the list. The further you move away from the boiler, you’ll find the lockshield valve will have to be opened more. The last radiator may need to have the lockshield valve fully open to work at full efficiency. Your radiators are now balanced and should work perfectly.

Getting A Temperature

A key part of this job is measuring the temperature difference across each radiator. Specially designed thermometers that strap round the pipes at either end of the radiator are available to buy or hire, but it’s not really necessary to use these. You can get away with a single digital thermometer — it just means that you can’t take simultaneous readings and you’ll have to move from one end of the radiator to the other.

Digital thermometers are available from around £10. Alternatively, some digital multimeters have a temperature sensor function. A digital multimeter with temperature function costs from £25 and can also be used for taking electrical readings and checking continuity in wires, among dozens of other functions.

 

[Rickster123]

It's posts like that croppie that are the reason you get paid the extra! Nicely done.

 

[Dotty]

It's posts like that croppie that are the reason you get paid the extra! Nicely done.

Ai Thenk Yew!

Not just a pretty face you know!

 

[TBServices]

OR you can fit Stelrad Radical radiators and take out all the mystery lol

 

[Ollieg]

The best flow temp is different in every home. The flow temp set on the boiler effects the reaction time of the heating system. My answer to my customers is "a low as possible to keep you comfortable". The optimum flow temp changes according to outside temp.
Have a look at weather compensation for an idea of how complex it is.

 

[DirksPlumbing]

Croppies post describes it all if you want to balance your system but if it is 8mm micro bore my advice would be to forget about balancing and try to keep valves (lock shields) as wide open as possible and let the controls do their work. Even on 10mm pipe it is questionable.

Choking a marathon runner to make him adjust to low oxygen conditions is likely to fail.

 

[Dotty]

Croppies post describes it all if you want to balance your system but if it is 8mm micro bore my advice would be to forget about balancing and try to keep valves (lock shields) as wide open as possible and let the controls do their work. Even on 10mm pipe it is questionable.

Choking a marathon runner to make him adjust to low oxygen conditions is likely to fail.

Nice analogy!

 

[AWheating]

condensing boiler 19 degree difference.
non condensing boiler 10 degree difference.

and 1 degree loss on the primary pipework give you 20 or 11 degree difference's on your boiler flow and return.

with a condensing boiler you want the flow about 70 and the return temp about 50 degrees, modern boilers modulate better to suit the system they are fitted to.


most engineers can/will balance from experience rather than spending hours on it. In an ideal world it would always be done correctly, but you have to compete with unregister'd/idiots engineers who dont even test gas pressures never mind balance the rads correctly.

 

[AWheating]

also do you have a brother called cottoneyejoe?

 

[dontknowitall]

Great post, Croppie!

(I must admit, although I thought that was the procedure it was good to have it confirmed :smile: )

A quicker and less scientific way (a method I read on here a while back) is to hold both ends. It should be "Ouch!" at one end and "Ouch you fekker!" at the other end.

 

[Whn1]

Great post, Croppie!

(I must admit, although I thought that was the procedure it was good to have it confirmed :smile: )

A quicker and less scientific way (a method I read on here a while back) is to hold both ends. It should be "Ouch!" at one end and "Ouch you fekker!" at the other end.

Haha That's the way we all do it.