Bypass valve

[Tonygeek]

But am I right in thinking that would not comply with the Building Regs? And I'm no expert, but I don't really understand how that helps with only needing a bypass during pump overrun and not at other times. If one were to go down that route, would it not be more logical to have something like a towel rail instead, which could provide a useful function, as well as being more effective at dissipating the surplus boiler heat during overrun?

 

[denso13]

But am I right in thinking that would not comply with the Building Regs?

Yes, neither does a zone valve. Life is too short...

 

[Johntheo5]

Hi again John.

I can’t see anything in the Installation and Maintenance Instructions about the HEx head loss. The only thing in the specs is “Available pump head at 20C system temperature rise = 2 metres”

I’ve done a set of readings at 60C set temperature but could try to do some at 70C if required:

Target flow temp set: 60C
Indicated flow temp: 63C
Actual flow temp: 67C
Actual return temp: 55C
Burner modulation: 27% (8kW)
Pump modulation: 57%
Pump map setting: 2 (200mb)

Can you have a look again sometime when the boiler is running steadily at the target & indicated flow temps and ideally, those or any other readings above.

 

[Tonygeek]

OK John. I'm taking the opportunity of the colder weather today to check the balancing of my whole system this evening but I will try to do some readings as above asap.

 

[Johntheo5]

OK, thanks.
Why (if you are) are you running with such a low (residual) head of 150mb, 1.5M, it's far easier to balance with a higher head, also, I would think most systems would require at least 200mb to run properly.