Yes, but those readings are all indicative of practically no circulation, if the pump discharge valve was closed fully, the readings would/should be the same, if I shut the discharge valve on my Wilo smart pump, the power readings will be exactly as its pump curves show for each different mode&setting at zero flow rates.
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- May 23, 2015
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Hard to disagree with that as 33W does seem very high for zero flow. Mine is 24W at zero flow, just tested it there now by shutting its discharge valve and its exactly as shown on its pump curve.
If the Alpha is re installed then quite simple to check it out by just shutting the discharge valve fully for 5/10 secs.
If the Alpha is re installed then quite simple to check it out by just shutting the discharge valve fully for 5/10 secs.
OK so no change with the Wilo pump.
To explain this fully:
I have lived here since a child. Now 35. House has always been cold but I've done major upgrades to Building fabric in recent decade.
Heating always worked largely OK but also some rads were off always and never checked out. Pipes are 28mm on GF, 22mm on FF and 15mm to all rads no less than that.
House was renovated & extended over the years a couple of times in 80s.
Boiler is on one side of house so it has a job getting around all rads and back to boiler.
If I balance rads by feel only I get them all working on GF largest zone except furtherest away. If I turn others off then the furtherest one will come on hot.
Problem is even when the first floor small zone is on, when I balance first 2 rads accurately with thermometer to 11 degree drop, they feel toasty but then the other rads drop dead.
I do still believe the house simply requires a larger output circulator. This problem has existed for years and the new boiler is cranking out the heat but getting nowhere. I think for these purposes the Trident 180mm pump is worth a trial at least. If it proves the theory and I can balance rads properly and not lose heat / flow then can invest in a higher quality pump for long term use. Probably talking light commercial circulator here which I think the Trident may be albeit a cheap one.
Sorry for poor quality but here is ground floor plan as example. Boiler is on far right wall.
It is back left bedroom that won't get hot when rads are balanced by feel only. Furtherest from boiler room
It is back left bedroom that won't get hot when rads are balanced by feel only. Furtherest from boiler room
OK better plan attached. (A bedroom single rad is removed at present)
Colour coded locations of rads on this Ground Floor. First floor is smaller on plan as it is a 1.5 storey house.
Colour coded locations of rads on this Ground Floor. First floor is smaller on plan as it is a 1.5 storey house.
- May 23, 2015
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Thanks for that, am I right in thinking those figures may relate to
25mm inlet
80mm pump vane?
If so yes that would make sense as old units are 15mm inlet and 60mm vanes
GF only.
Does the boiler start to cycle a few minutes after a cold startup in the morning or does it run continuously for say 25/35 minutes before cycling?.
You have 28mm on the GF so a flowrate of 20LPM assuming 50M of pipework will require ~ 1M pump head, add another 1M for loss across rads etc then total head required = 2M so assuming no sludge in the system it should be no big deal to get sufficient circulation at least on the ground floor.
U/stairs with 22mm piping will require 3.4M to overcome pipe losses at 20LPM and 50M of piping, add another 1m across rads and total head required is 4.4M so a bigger problem for upstairs circulation.
Does the boiler start to cycle a few minutes after a cold startup in the morning or does it run continuously for say 25/35 minutes before cycling?.
You have 28mm on the GF so a flowrate of 20LPM assuming 50M of pipework will require ~ 1M pump head, add another 1M for loss across rads etc then total head required = 2M so assuming no sludge in the system it should be no big deal to get sufficient circulation at least on the ground floor.
U/stairs with 22mm piping will require 3.4M to overcome pipe losses at 20LPM and 50M of piping, add another 1m across rads and total head required is 4.4M so a bigger problem for upstairs circulation.
On cold start it will run for 15 or 20 mins then start cycling. Pipes in boiler room are roasting hot and return pipe always only max 25c at any time. (Usually return is stone cold)
I timed the cycling and of course this will vary with temps etc but it will stay off for 2.5 minutes and run again for 1.5mins. Does this constant. Pipes hardly touchable in boiler room so hot. Which makes me think the pump isn't drawing the water quickly enough around the circuit.
As I say I can get all rads to warm up bar one but not cranking enough room heat or near 11c drop.
I timed the cycling and of course this will vary with temps etc but it will stay off for 2.5 minutes and run again for 1.5mins. Does this constant. Pipes hardly touchable in boiler room so hot. Which makes me think the pump isn't drawing the water quickly enough around the circuit.
As I say I can get all rads to warm up bar one but not cranking enough room heat or near 11c drop.
Good bad or indifferent I just bought a Trident 25/80 180 pump. Cheap enough to test anyway. If I'm wrong then so be it can set on garage shelf! Will be a pain to drain system again to open up pump from 130 to 180 but space to do it.
Really grateful for the great advice on here keep it coming! And of course I will let you all know in any event what difference if any the new pump makes and if it then allows me to balance rads properly without losing circulation.
Just want to keep after it now and get the heating system fully up to snuff if I can.
Really grateful for the great advice on here keep it coming! And of course I will let you all know in any event what difference if any the new pump makes and if it then allows me to balance rads properly without losing circulation.
Just want to keep after it now and get the heating system fully up to snuff if I can.
Something very strange going on, assuming boiler flow temp set to 70C then when the burner cuts out with a return temp of 25C means that you are only circulating 6LPM (0.36M3/hr) which equates to the 38W pump output you mentioned previously.
A running time of 37.5% is a average output of 7.5kw with a 20kw boiler or 9.75kw with a 26kw.
Can/have you checked that the circ pump stays running when the burner cuts out.
A running time of 37.5% is a average output of 7.5kw with a 20kw boiler or 9.75kw with a 26kw.
Can/have you checked that the circ pump stays running when the burner cuts out.
Yes pump definitely stats powered up and all heating controls / valves are functioning correctly too
I will check water quality when I drain it again and if dirty at all then I'll get more cleaner and run again with new larger pump. But water now coming out of rad vents is practically clear.
I do flush it out every few years too. I recall first time I did it when I was about 18 the water was pitch black and some rads had to come off and be flushed out with hose. Again this was 15 - 20 years ago.
I do flush it out every few years too. I recall first time I did it when I was about 18 the water was pitch black and some rads had to come off and be flushed out with hose. Again this was 15 - 20 years ago.
Upstairs has been running on its own tonight for a couple hours. 2 double rads hot and bathroom tall single hot.
On time = 1.5 mins. Off time= 4 mins 45 secs.
Return temp 43c
Again on the small upstairs zone I can get all rads warm. But when I balance first 2 correctly the rest fall off cold even with valves fully open.
It's on the larger downstairs circuit that the return temp never rises above 25c even after hours of running.
On time = 1.5 mins. Off time= 4 mins 45 secs.
Return temp 43c
Again on the small upstairs zone I can get all rads warm. But when I balance first 2 correctly the rest fall off cold even with valves fully open.
It's on the larger downstairs circuit that the return temp never rises above 25c even after hours of running.
Last edited:
- May 23, 2015
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- May 23, 2015
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Yes probably could freeze it except I don't have any of that equipment!
It's easy enough to drain down anyway I suppose. stopcock for header tank easily reachable at trap door. Pop hose on boiler and let it run. If I don't crack the bleed screws on the rads most of them tend to stay full anyway.
New pump dispatched today by 24hr service so should have it tomorrow and will tackle replacement Friday night probably need to pick up some 28mm olives too.
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