Inadequate Circulator Pump?

[John.g]

Here are are the pump curves for a UPS 3. which IMO are quite adequate for your system with that 26kw boiler. On speed 3 it will circulate 2.0M3/hr @ a 4.3M head to satisfy a power rating of 26kw at a dT of 11C.
The Alpha 2 will only circulate 2M3/hr @ a 3.2M head. The pump in the photo is only showing 13W?.

 

[JC22024]

Here are are the pump curves for a UPS 3. which IMO are quite adequate for your system with that 26kw boiler. On speed 3 it will circulate 2.0M3/hr @ a 4.3M head to satisfy a power rating of 26kw at a dT of 11C.
The Alpha 2 will only circulate 2M3/hr @ a 3.2M head. The pump in the photo is only showing 13W?.

View attachment 67141

View attachment 67140

Yes I was trying different settings there but no difference. It has been on speed 3 ever since at 40w ish consumption. But can't appear to get beyond 2no first rads even on first floor circuit only! (When 11 degree drop is set on lockshields of first 2. Remaining rads full open and still dead)

Thanks for the curves - I believe it is a upm3 25-70 that was suggested? The pump has to travel quite a route from boiler room that's where I'm coming from VS boiler output. Which is downsize from old 26-32kw boiler due to more efficiency when using one zone or the other. (Since now the house is in 2no zones and I operate them independently)

 

[JC22024]

The head in my house is 6m. (Heating tank at top of loft)

So Grundfos - old @ 0.6m3/hr

Ups3 25-70 @ 0.8m3/hr

Doesn't appear like huge upgrade if my current pump isn't faulty but is undersize

EDIT - I may be reading the new pump chart incorrectly. It shows 5no curves so those must represent speed settings. In which case it could pump up to 1.5m3/hr

 

[John.g]

The elevation (height) of tank at 6M (or even 10M) doesn't mean that you need a 6M pump to overcome that head as its a closed system, if the flow&return piping are well sized then it may only require a pump (differential) head of 3M to overcome the pipe friction + other losses. Realistically, I would think you require a pump that will give a head of 4M at whatever flow rate you require. My 26kw Firebird boiler came with a nozzle sized to give 20kw output and yours may be likewise.

Which "new pump chart" are you referring to?, if its the Trident can you post the link to it?.

 

[JC22024]

The elevation (height) of tank at 6M (or even 10M) doesn't mean that you need a 6M pump to overcome that head as its a closed system, if the flow&return piping are well sized then it may only require a pump (differential) head of 3M to overcome the pipe friction + other losses. Realistically, I would think you require a pump that will give a head of 4M at whatever flow rate you require. My 26kw Firebird boiler came with a nozzle sized to give 20kw output and yours may be likewise.

Which "new pump chart" are you referring to?, if its the Trident can you post the link to it?

OK I presumed that as it is open vent system atmospheric pressure would have meant it was operating at lowest point of 6m head of water.

I don't have a curve for the Trident pump.

I was looking at a Grundfoss PDF which gave just one curve chart. And mentioned specific charts available per pump. Found a chart which may be pump specific in the link below:

Grundfos UPM3 Auto L 25-70 130mm Underfloor Heating Pump 240v

Buy Grundfos UPM3 Auto L 25-70 130mm Underfloor Heating Pump 240v Online at Anchor Pumps, Find the Best Price Anywhere Online, With Free Delivery.

www.anchorpumps.com

Swipe to the 2nd image for pump chart. It does appear to read more powerful than the older pump and I'll probably go for this Grunfos one as recommended

 

[ShaunCorbs]

Upm3 at 3.5 on speed two gives you approx 1.8m3h speed 3 2.5m3h

 

[John.g]

I suppose still slight chance that the pump is ok but blockage in main flow or return, as the pump is running at 38/40W then hard to see actual head/flow so suggest just c/o to CP1 & CP2 for a minute or two each and note the power, that might give a better idea of pump condition.

 

[JC22024]

I suppose still slight chance that the pump is ok but blockage in main flow or return, as the pump is running at 38/40W then hard to see actual head/flow so suggest just c/o to CP1 & CP2 for a minute or two each and note the power, that might give a better idea of pump condition.

OK after running on larger downstairs zone for 45 mins or so on speed setting III is was reading 33w.

On CP1 5w
CP2 7w after a few mins.




I remembered I had set the old circulator pump on garage shelf as a spare incase it failed. So I pulled it out there and slapped it in to see if it makes any difference to this as you say could also be a blockage.



The water I drained out of the system was light brown / clear. Not black. I had a Sentinel cleaing agent in it there for a week or so and drained down completely + re filled at weekend with new ball cock installed in header tank also. (Trying just to maintain the whole system)

Again the water I drained after the flush I did monitor and it was clear / light brown. So hopefully not a blockage per say but need to be mindful of that too thanks.

 

[John.g]

That old Wilo should certainly provide enough head for one zone on top speed.
There seems to be something wrong with the Alpha as the minimum power on CP1 is 13W and on CP2 is 22W, the minimum outputs on PP1 & PP2 are ~ 4.5W and 6W, more or less what you got.

Also (if I am looking at the right pump curves) the power output on speed3 when pumping 0 LPM is 33W!!.
If the Wilo is looking promising you might take the head off the Alpha and inspect/clean the vanes of the pump impeller and the pump ports, you might be able to clean the pump rotor at the same time.

 

[ShaunCorbs]

Jon it’s a 20 rad system