new modulating heating pumps

corkgsxr

Anyone know how they work out what output they need?

Iv had a few open and they look no different to traditional pumps on the wet side.

Is it heat or flow?

If it's heat should they be moved to the flow

John T Carroll

corkgsxr wrote: »

Anyone know how they work out what output they need?

Iv had a few open and they look no different to traditional pumps on the wet side.

Is it heat or flow?

If it's heat should they be moved to the flow

These are variable speed high (motor) efficiency circulating pumps. Grundfos and Wilo are some of the manufacturers. they claim 80% savings over the older type fixed (3) speed type. They have two selectable modes of operation, constant differential pressure control and variable differential pressure control.
I have looked at the pump curves for the 6M Wilo Yonis Pico as a friend of mine is thinking of replacing his 15 year old. They certainly seem to be very efficient, for example if one runs the 6M Wilo on a constant differential pressure of 4M then the flowrate will be 22.5 LPM at 35Watts, if the flowrate halves say due to zoning etc then 4M at 11.25 LPM will draw 23Watts, if the pump is now switched to variable differential pressure control then the pressure will be controlled at 3M and will only draw around 16Watts at the same 11.25 LPM. Another claimed advantage is that as the flowrate is indirectly controlled then a higher delta T is maintained across the boiler which helps efficiency.
I don't know if high efficiency 3 (fixed) speed pumps are available or not now but one would think that if so that they would have a longer life due to less complexity and while they might average say 25Watts vvs 15Watts for the smart one they might still be a better choice if sized properly for the application?.
Based on my own CH usage and circ pump power of 43watts then I reckon I would save around €11/annum against a smart pump drawing 17 Watts.

Wearb

John T Carroll wrote: »

Based on my own CH usage and circ pump power of 43watts then I reckon I would save around €11/annum against a smart pump drawing 17 Watts.

My pump uses 80 watts on its low speed setting. It is an old pump, but working away.




I would guess that the modulating pumps must be working on both temperature and pressure readings to adjust their flow rates.

John T Carroll

Wearb wrote: »

My pump uses 80 watts on its low speed setting. It is an old pump, but working away.




I would guess that the modulating pumps must be working on both temperature and pressure readings to adjust their flow rates.

They certainly use the "rotational speed and the current draw to see where they are operating on the pump curve" at any rate so whatever they are using it seems clever enough.
Do you know if high efficiency fixed speed pumps are on sale here legally or must everyone now use these smart ones?.

Wearb

Around here the old fixed speed ones are very difficult to get.
I remember that there was a very good argument for using the old ones in certain installations, but for the life of me, I can't remember it now.

corkgsxr

Wearb wrote: »

Around here the old fixed speed ones are very difficult to get.
I remember that there was a very good argument for using the old ones in certain installations, but for the life of me, I can't remember it now.

I don't think the new ones will fit a systemlink


Any time I fit them they seem to want to cut Down to 7/8 watts. Seems very low

John T Carroll

corkgsxr wrote: »

I don't think the new ones will fit a systemlink


Any time I fit them they seem to want to cut Down to 7/8 watts. Seems very low

It might seem a bit low but could be quite accurate, in the example above, 11.25 LPM at a 3M head on the 4M setpoint drawing 16 watts would only draw 12 watts at a 2M head if on the 3M setpoint. 11.25 LPM at a boiler delta T of 15C is a heat load of 11.8 Kw/hr which most well insulated houses would hardly need, once up to temperature. There certainly seems to be substantial energy savings especially if a bit of time is devoted to tuning the pump set points.

John T Carroll

Wearb wrote: »

Around here the old fixed speed ones are very difficult to get.
I remember that there was a very good argument for using the old ones in certain installations, but for the life of me, I can't remember it now.

I had another good look at those smart pumps last night and I don't think temperature plays any part in their calcs, in my opinion they do measure the differential pressure and derive the flowrate from the pump speed and the power drawn. When selected to variable differential pressure they will then ramp the speed down (or up) within limits which will reduce the flowrate through the radiators (or heat exchangers) and therefore increase the delta t in the boiler.

Re not working in certain installations (systemlink?), If they are ran in the constant differential mode at the highest setting then I really cant see why they shouldn't perform the same as the traditional fixed speed circ pumps. Lowara make one of these smart pumps with stepless speed control so again if set to the highest setting then should perform like their fixed speed counterparts?.

I have cobbled together a little spreadsheet based on the limited data to hand that you (or anyone) may find interesting as you can change the speed and see the effect that this makes to the pump head and flowrate.

corkgsxr

Problem with systemlink is they don't fit between the bars

roy rodgers

If you look closely on the right I've fitted then wilo pumps to a system link

corkgsxr

roy rodgers wrote: »

If you look closely on the right I've fitted then wilo pumps to a system link

Maybe a old version I had. It had short and long steel pipes

Pumps on the short.

I donno was it only the dab that would fit