Balnced rads now what about boiler flow rate?

[tukky142]

Hi,

I have balanced all my rads so that each one has around a 20 degree drop. I have measure the input/output pipe temperature into the boiler and they both measure the same. Should the pump speed be altered so that there is a 20degree drop at the boiler?
I have a potterton 28i boiler - does this boiler have a pump that is automatic?
What are the benifits for slowing the pump down?

Thanks in advance

 

[JPC]

balancing rads is used to make sure all rads warm up roughly equally and similar speed. (ie close rads dont take all the warmth)
cant see how u managed a 20degree c drop from one end of the rad to another ?
i beleive a 11 degree drop between f and r at the boiler is about right.

 

[kevplumb]

I have balanced all my rads so that each one has around a 20 degree drop. I have measure the input/output pipe temperature into the boiler and they both measure the same.

how can they if your dropping 20c across the rads

 

[tukky142]

20 degrees f not c - the last in the chain does not drop 20 but most of them do

 

[kevplumb]

so the return water must be cooler than the flow

 

[ChrisR]

All a bit academic?
Potterton 28I - NO you can't alter the pump speed it's needed for HW. (Unless I'm wrong again)

 

[chrishutt]

I have measure the input/output pipe temperature into the boiler and they both measure the same.

Try it again but when the boiler is firing.

 

[Paul Barker]

With condensing you want 15 to 20 degrees C. With a regular boiler 11 degrees C.

If you achieve it you're unusual because you've been titting about for two days.

 

[tukky142]

Thanks for your comments guys.

I will take some more measurements tonight after leaving the boiler on for a while. Can the boiler be adjusted to get the right temp drop? - does it really matter??

 

[chrishutt]

Can the boiler be adjusted to get the right temp drop? - does it really matter??

Not easily, and no.

Basically if you have an average temperature drop across the heat emitters (radiators) of say 20 C, then you will have the the same temperature increase across the boiler, assuming that the boiler is firing continuously on full gas rate throughout the test period.

In practice this won't be happening (since the boiler output is far more than the heat input to CH - it will modulate and switch off for periods). So don't worry about it. The Potterton 28i may permit adjustments to be made to the CH output, but this can only be done by a gas engineer (or equally competent person). But since the output modulates anyway, there isn't much point.