Need to re-balance heating after drain down :(

[kennystarsky]

Heating question I'd like some help with if i may please--
we drained our system down to remove all radiators to decorate our whole house up. we thought it better to drain whole system than to take off each radiator on its own.


now we have a problem! we closed all lockshield valves and didn't count the turns! so we have not got a balanced heating system now.

it is summer so no probs at the moment but i'd like to balance it so it is ready and done.

i have read about finding the INDEX CIRCUIT? if that makes sense? do i need to find this and measure the temperatures? or do i measure the boiler flow and return pipe temperatures, and maintain this temeratue difference across all radiator flow and returns?

please hep as i feel a right wally


all the best, ken.

 

[D_Hailsham]

i have read about finding the INDEX CIRCUIT?

The index circuit has to be determined when selecting the correct pump. As this has already been done, you don't need to bother about it.

Balancing Procedure

 

[kennystarsky]

thanks for the link. i will read it through now!

the index circuit is to do with the pump then.. sounds interesting. is there any link so i can read up about that as it interests me now (sad i know)!!

thanks again.

 

[kennystarsky]

What infrared thermometer from maplin would you recommend? or what clip on types? I have never seen any before in the shops?.... do screwfix sell them?

 

[steved101]

With a new low water content condensing boiler, the pump speed is usually always set to speed setting 3 (the highest setting), due to the fact that the boiler requires a fast flow rate through its heat exchanger, to prevent the water overheating/boiler going to lockout, and thus boiler noises.

 

[D_Hailsham]

What infrared thermometer from maplin would you recommend? or what clip on types? I have never seen any before in the shops?.... do screwfix sell them?

Clip on thermometers can be got from any plumbers merchant, but I would not recommend them as they are not very accurate and are very slow reacting to temperature changes.

Any IR thermometer will do, you don't have to spend a lot of money. If possible choose one with a high distance:spot ratio. Think of it as a torch beam - the higher the ratio the more concentrated the beam. You want to measure the temperature of the pipe, not the pipe and the wall behind. With a low ratio you would need to be touching the pipe to get a sensible reading.

For index circuit read Copper Tubes in Domestic Heating Systems

 

[D_Hailsham]

With a new low water content condensing boiler, the pump speed is usually always set to speed setting 3 (the highest setting), due to the fact that the boiler requires a fast flow rate through its heat exchanger, to prevent the water overheating/boiler going to lockout, and thus boiler noises.

Not strictly accurate.

The flow rate is determined by the power output of the boiler from the formula: Flow = Power divided by (4.2 X temperature difference). The reason for running the pump at full speed is that the resistance through a modern heat exchangers is very high, so the total head which the pump has to overcome has increased.

For example, the Vaillant ecoTEC Plus 415 has a pressure loss of 1.35 metres. While the 20 year old Myson Apollo has a loss of 0.7 metres and a Potterton Kingfisher 80Cf has a loss of about 0.1 metres.

 

[kennystarsky]

thanks for your help.

from the maplin site, are any of these in your opinion good ??

http://www.maplin.co.uk/Search.aspx?criteria=infrared thermometer&source=15



i'd like it to balance the rads well, and also as an added bonus, as D_Hailsham kindly mentioned, for testing for cold spots on rads (for sludge build up, etc).

 

[Goldspoon]

I have this one:

http://www.maplin.co.uk/Module.aspx?ModuleNo=221048

I think it is excellent.

Make sure you add some matt tape to the surface you are measuring as these do not like shiny surfaces. I use masking tape - normal beige stuff.

 

[D_Hailsham]

from the maplin site, are any of these in your opinion good ??

http://www.maplin.co.uk/Search.aspx?criteria=infrared thermometer&source=15[/QUOTE]
I would go for the first one as its accuracy is slightly better.

When you measure the pipe temperature, get the gun as close to the pipe as you can; it doesn't matter if you touch the pipe.

If you find that the readings vary considerably, this may be because of the different emissivity of the surfaces - painted, unpainted etc. The way to overcome this is to wrap the pipe with some black insulating tape, so you are reading off a consistent surface.