On 11/11/17 16:59, John Rumm wrote:
On 11/11/2017 11:44, Tim Watts wrote:
I've balancing my new CH - noticed the flow and return to the boiler
were virtually the same - and the auto bypass valve was set to minimum
(0.1 bar = 1m head water IIRC)

Closing it down to 0.4 bar has jumped the differential temperature - but
I suspect that's too high.

The Worcester manual says the pump can deliver 2m head for "21C
temperature rise" - nothing else about min flow rates or bypass pressure.

Any ideas? If I turn it to 0.2bar the flow temperature starts to creep
up.

Now this may also suggest I have the lockshields all turned down too low
as well (I've opened 1/4 - 3/4 turn as a starting point).


I have mine set pretty high - based on the assumption that I only want
it to do anything when nearly all the TRVs are closed off. A highish
differential temperature should keep condensing efficiency up as well.


Thanks John.

After balancing round 1 (a differential thermometer with 2 pipe clamps
certainly makes this quicker!), I have 10-12 across all rads more or
less at a flow to rad of 56C (boiler indicates more like 65C internal).

Fiddling with the bypass, it seems to start shunting big time at a bit
under 0.4bar - so I have set it a smidge over.

The plan is now to turn the boiler down to about 55C flow - I have
oversized the rads as far as possible with a low flow temperature (and
spare in a really cold winter) in mind.

Think I'll have to go around one more time in a couple of weeks.

Next problem - it's bloody hot upstairs and there are no radiators.

But there is about 50-70m of exposed pipework!!!

It's been quite tightly run (linked Talon clips) and I cannot get 13mm
thick insulation on it. So I'm off to peruse the Internet for either
some thinner tube, or I'll have to box it in (and be damned if the flow
heats the return a bit).

Overall - very happy. I have boiled everyone half to death running it
flat out all day. That is very nice - this house has never been this warm