Inadequate Circulator Pump?

[John.g]

Have you measured the dT across any of the rads yet?

 

[JC22024]

Have you measured the dT across any of the rads yet?

I can do that in the coming days, should I leave the heating running for a couple of hours before I measure that?

 

[John.g]

You can do it anytime after the boiler starts cycling (like now), just take it off one or two, but before the burner cuts out, any idea what the on/off cycle times are now?

 

[JC22024]

You can do it anytime after the boiler starts cycling (like now), just take it off one or two, but before the burner cuts out, any idea what the on/off cycle times are now?

We are away this evening so I'll turn it on tomorrow when I get home, time etc and report back.

What I did not earlier was a 20c difference in the boiler feed and return temps. I think this is fairly optimal(?) On speed 2 after it had been running for an hour or so

 

[ShaunCorbs]

Yes 20 is spot on for the boiler

 

[John.g]

That's more like what I would have expected alright as it means that the flowrate is actually, 26*860/60/20, 18.6LPM, which makes more sense with a pump running with a constant head of 6M.

 

[JC22024]

How to calculate the

After you have worked out the heat requirement for your room (AEL's easy-to-use BTU calculator will help you do this), how can you check that the radiator you have chosen will provide enough heat output? There is a simple calculation to check if the radiator will provide sufficient heat output...

www.buildingservicesindex.co.uk

Should I be waiting until the radiators are balanced before taking the above readings? Or for now, prior to proper balancing taking place just shoot the centre of the rad for an average temp across the ground floor?

 

[John.g]

No need to wait for balancing just now, the easiest quick test for now is to time say two on/off cycles, and then take the boiler flow and return temps while boiler is firing and as close to burner cut out as possible, ie if burner run time is say 2 mins, take flow&return temps after say 90secs or so and I can calculate the average rad(s) output and temps based on these and the boiler cycle times.

 

[JC22024]

No need to wait for balancing just now, the easiest quick test for now is to time say two on/off cycles, and then take the boiler flow and return temps while boiler is firing and as close to burner cut out as possible, ie if burner run time is say 2 mins, take flow&return temps after say 90secs or so and I can calculate the average rad(s) output and temps based on these and the boiler cycle times.

Yes I'll do that this evening and mark current return / feed temps on the rads on the GF plan.

Then will balance later this week. Will clean the mag filter each day - more so to use the dosing capacity to get the new 2L of X800 into the system. Then after boxing day I'll drain and flush the whole system for final time and add inhibitor

 

[JC22024]

OK, heat has been on for a few hours downstairs zone only. It was at the 19.5c digital stat setting in living room so I think was likely OFF for a while before I got to testing it.

Hence readings may have been when it was warming up again :

72c out
54 return
7.5 mins run tune
1 min off time

Note I just took a temp reading at top middle of each rad. Then the last one which was always cold flow and return temps too.

Hasn't been balanced properly yet but appears decent spread all the same. (I had just balanced by hand feel last week) Pump on speed setting two still.

Bedroom 2 rad is off as room being refurbished at moment. I will get a new double Myson rad and liquid Drayton TRV for it this spring.

Utility will be Knocked down this summer so it's rad is off possibly for good.