Central heating pump sizing

[John.g]

I have read on him yes. Im just running numbers and trying to figure out the resulting flow from the square root of head. Clearly im not doing something right

You mean mathematically?. if a differential head of 3M results in a flow of say 13 LPM (like my heating system) and I increase the (pump) head to say 5M, the resultant flow will be the original Flow X the sqroot of the (newhead/oldhead).....13X sqroot(5/3) = 13X1.29 = 16.77 LPM.

 

[SJB060685]

You mean mathematically?. if a differential head of 3M results in a flow of say 13 LPM (like my heating system) and I increase the (pump) head to say 5M, the resultant flow will be the original Flow X the sqroot of the (newhead/oldhead)***..13X sqroot(5/3) = 13X1.29 = 16.77 LPM.

Thanks buddy. That makes sense now

 

[Reddwarf4ever]

You mean mathematically?. if a differential head of 3M results in a flow of say 13 LPM (like my heating system) and I increase the (pump) head to say 5M, the resultant flow will be the original Flow X the sqroot of the (newhead/oldhead)***..13X sqroot(5/3) = 13X1.29 = 16.77 LPM.

Although they both have this part number DAB 60161174, the images look different......the Amazon one is more expensive Andries than even look like it has the data display.....
Will phone PSD tomorrow and confirm, think this is my best hope, seems a very good price £62.39 inc free postage....any thoughts ? 1st image PSD 2nd image Amazon

 

[John.g]

Every time one looks at these pumps they seem to change spec/display, Grundfos is the same, they must be breeding them, just ensure you are getting the one with the proper display.

 

[Reddwarf4ever]

Every time one looks at these pumps they seem to change spec/display, Grundfos is the same, they must be breeding them, just ensure you are getting the one with the proper display.

That’s the one on the left, curious how prices vary, £60-£150.....eBayera are an optimistic breed

 

[Reddwarf4ever]

Every time one looks at these pumps they seem to change spec/display, Grundfos is the same, they must be breeding them, just ensure you are getting the one with the proper display.

Problem is, I have just been advised this is a 180mm length pump whereas mine is 130mm, is that correct ?

 

[John.g]

A bit surprised at that, don,t know dimensions of your own one, the wilo gives practically the same output, will check in morning to compare and advise, measure your own to confirm 130mm

 

[John.g]

A bit surprised at that, don,t know dimensions of your own one, the wilo gives practically the same output, will check in morning to compare and advise, measure your own to confirm 130mm

The DAB3 appears to be a 8M pump hence the 180mm between centers so I would advise against this as it involves piping mods and drain down, also 130mm centers gives you more choice of 6/7M pumps.

While the Wilo or Dab Evosta2 (no display) will almost certainly give you the required head/flow I think you are better off installing a pump like a Grundfos UPS3 15-50/65 which is very powerful 6.5M pump which will satisfy your needs with ease. For example it will pump 33LPM @ 4.5M, Dab2, 33LPM @ 3M and the Wilo 33LPM @ 3.2m.

Unfortunately, this UPS3 does not display watts but not the end of the world as you really only need this as an aid to see if you have a pump problem or a restriction. By spending a few extra bob you can buy a nice little plug in energy monitor, I have a few and they are quite accurate, (see link) and use it like this.

I assume you intend to clean the existing pump head so before removal/clean, remove the pump lead and fit a 3 pin plug. ensure boiler off and any zone valves if fitted, latched open, plug in the pump lead to the energy monitor in turn plugged in to any convenient socket or extension lead, note the watts, remove plug, clean pump head and ports, then re measure power.
Depending on findings, if you do decide to install the UPS3 or whatever, do likewise, stick a 3 pin plug on it and you can then monitor its power in its different operating modes and then run the pump on the appropriate setting. When tests complete re install pump lead to wiring center.

One word of caution if removing the pump by opening the isol valve nuts, these can be extremely difficult to undo, I have change out a few pumps for neighbors and one of my own and have always drained down and removed the pump complete with isol valves, I then found it quite difficult to remove the pump valves even though I obviously renewed them with the new pump.

https://www.amazon.co.uk/Monitor-Electricity-Display-Consumption-Analyzer/dp/B08KZGM1P7/ref=asc_df_B08KZGM1P7/?tag=googshopuk-21&linkCode=df0&hvadid=463168730140&hvpos=&hvnetw=g&hvrand=3905167764382884732&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007835&hvtargid=pla-1020257457799&psc=1

PS: fairly sure your pump has 130mm centers but best to measure up.

 

[Reddwarf4ever]

Thanks for all the advice, sounds like the way to go.....will investigate the power to my pump, looks rather complicated, as this also had its wiring modified.....when an electrician came round a few years ago, he made some changes, involved lifting up the floor board to get access o the connections ( my dam extension buile
der ) found he had used a light switch as a junction box, now the new junction box in the immersion cupboard, but looks complex.....will have a careful look, taking photos as I go....all good fun what’s the LPM of the DAB3 ? Do like the idea of the displays, womder how it displays the flow, ant be a calculation as it doesn’t know the Delta T, must be an integral flow meter

I don’t suppose a replacement pump comes with new valves, assume would have to be bought separately my CH pump iso valves have no handles, never have, can these be bought separately ? Be so much easier to isolate

 

[John.g]

Your old pump isolating valves are probably 1/4 turn ball valves that you shut with a screwdriver (slot) or a allen key, nothing sticks out, but unfortunately they almost always leak after operation, you can easily buy new ones with gate valves.

It would seem that you can get a Dab Evosta3 with 130mm centres. it might be a 6.5/7M pump but you should ask your supplier if they have one, this will also be adequate IMO, the pump curves for all their models are in the link.

https://evosta.dabpumps.com/wp-content/uploads/2019/03/Evosta-2-3-Installation-and-Operation-Manual_UK.pdf