CH pump replacement concerns.

[diydave]

Hi. My Parker 15-60 130 pump has been running fine for 7 years at its highest speed. It has recently developed a knocking sound when hot and working hard (disappears on speed 2) but this is not fast enough for my 15 radiator bungalow. Bleeding the pump had no effect so I suspect it might be on its way out and am considering upgrading to a grundfos UPS3... but I see here on the forums that these pumps can give problems through being too powerful? Any comments? Might I be better with a Salus 100A or 200A which also have auto pressure facility. (Also much cheaper!)
Cheers
David

 

[diydave]

Nobody willing to comment??

 

[John.g]

The UPS3 wouldn't be top powerful, it's their choice of PP settings that I don't like, I would suggest that Dab evosta3 is a better choice as it shows you the power, the head and the flowrate OR a pump like my own, a Wilo Yonos Pico 6m where you can set the PP & CP modes in 0.
1M increments.

 

[John.g]

Forget Auto Adopt as it rarely works on any make of pump. If you indent to add more or bigger rads then a 8M Wilo might be a good choice too.

 

[John.g]

Can't edit on my ancient Iphone but thinking re above again the DAB is possiy the fit for you as it is actually a 7M (4m/7m) pump.

 

[diydave]

Thanks John. I'll check out the DAB. At first sight it seems rather underpowered given my old pump used to have to run flat out at about 90W. I previously understated my radiator count... its actually 19.

 

[John.g]

Thanks John. I'll check out the DAB. At first sight it seems rather underpowered given my old pump used to have to run flat out at about 90W. I previously understated my radiator count... its actually 19.

Thanks John. I'll check out the DAB. At first sight it seems rather underpowered given my old pump used to have to run flat out at about el90W. I previously understated my radiator count... its actually 19.

You require a 8m pump definitely so, DAB a good choice but only if they make a 8m model otherwise a wilo 8m IMO,

 

[diydave]

Thanks John. A DAB it will be. But I cannot justify the higher, triple, cost of an Evosta 3 80. Just have to decide if the (more highly specced) Evosta 3 60 (marginally lower pressure/flow than my current), or the simpler Evosta 2 40-70 (marginally higher) will do the trick

 

[John.g]

Hadn't realised that the evosta3 has a lower output than the evosta2 looking at the evosta2 curves then assuming 19 rads @ 1.5kw each, a 10c dT will require a flow of - 2.4m3/hr so pump head is around 2m, too low but if a dT of up to 15c is ok then head is around 3.8m so there or there a outs and probably ok.
John

 

[diydave]

Hadn't realised that the evosta3 has a lower output than the evosta2 looking at the evosta2 curves then assuming 19 rads @ 1.5kw each, a 10c dT will require a flow of - 2.4m3/hr so pump head is around 2m, too low but if a dT of up to 15c is ok then head is around 3.8m so there or there a outs and probably ok.
John

Thanks John. Very helpful.

 

[John.g]

Let us know how you finally get on.

 

[diydave]

Let us know how you finally get on.

Old pump has gone quite quiet since it learned it was going in the bin!! Waiting Boiler Service Engineer's advice coming soon and Dab Evosta2 or 3 will be ordered thereafter as required.
Thanks again for help.

 

[diydave]

Eventually went for Evosta 3 'cos a well known online supplier had a bargain on his Ebay shop! Running like a dream with good flow/return temp diff throughout using Proportional 3.

 

[John.g]

What is the pump power output and flowrate with those 19 rads?? Is it a 8M pump?

 

[diydave]

6m pump John. I'm running it at Proportional 3. 34W 4.2m head 3.3cu m per hour initially. Will monitor it more closely after I've rebalanced the rads. 13 of the rads have thermostatc valves so I expect to see differences as house warms up.

 

[John.g]

I interpret from the pump curves that the flowrate is 1.02m3/hr, 17.0LPM which, depending on the rads output may give a dT of 15C to 20C.

 

[John.g]

 

[diydave]

Apologies John. Typo on my part. Indicated flow rate is indeed 1.3 cu m per hour and your delta T of between 15 to 20 deg C across the boiler is spot on. Delta T across radiators is very variable because of thermostatic valves. Delta T across boiler drops when hot water cylinder calls.