Which is the more powerful pump?

[Ben-gee]

Shaun OP is saying dead legs when what he actually means is drops.
This is a case of a little knowledge is a bad thing!

 

[ShaunCorbs]

Shaun OP is saying dead legs when what he actually means is drops.
This is a case of a little knowledge is a bad thing!

Agreed kinda guessed that also probably old back boiler with I’m guessing when removed flow and return linked hence why no flow to the rads as it’s talking the easiest route

 

[rcpilot]

Give us the numbers then please , and the PP setting, should be a good indication of whats happening.

Hi all well what I did was shut off all the upstairs rads so just the downstairs rad were open, set the pump to constant curve @100% operating mode @Max estimated head was 5.9 m and the speed was 5295.
The sitting room rad (which is the new big one) got hot but I could not balance it, the kitchen one which was cold or just barely warm was heating up but did not get hot, the entrance rad was still cold, my conclustion is either the pump cannot push the water round the system (all the above rads are on dead legs) or there is a blockage or trapped air in the return legs, which all I can do is bleed the return legs (not the rads) and see if it makes any difference, if it does not then the only solution is to find a much more powerful pump, if anyone can tell me what would happen if I fitted a commercial pump, of which I have the specs :- UP UPS 14m3/h 13m head pmax 10bar
UPS 25-80 :- 8.5m3/h 7mhead

 

[rcpilot]

Agreed kinda guessed that also probably old back boiler with I’m guessing when removed flow and return linked hence why no flow to the rads as it’s talking the easiest route

When I took out the back boiler I renewed the upstairs pipework to 15mm flow and return, the downstairs (as the boiler is upstairs) was put on dead legs or drops 15mm flow and return

 

[ShaunCorbs]

Do the test again but shut all but one rad eg one problem one does that get hot ?

 

[John.g]

Hi all well what I did was shut off all the upstairs rads so just the downstairs rad were open, set the pump to constant curve @100% operating mode @Max estimated head was 5.9 m and the speed was 5295.
The sitting room rad (which is the new big one) got hot but I could not balance it, the kitchen one which was cold or just barely warm was heating up but did not get hot, the entrance rad was still cold, my conclustion is either the pump cannot push the water round the system (all the above rads are on dead legs) or there is a blockage or trapped air in the return legs, which all I can do is bleed the return legs (not the rads) and see if it makes any difference, if it does not then the only solution is to find a much more powerful pump, if anyone can tell me what would happen if I fitted a commercial pump, of which I have the specs :- UP UPS 14m3/h 13m head pmax 10bar
UPS 25-80 :- 8.5m3/h 7mhead

You are pumping practically NIL as you can see from the pump curve that the flowrate at 5.9M is 0.
The pump power is 22/23kw, you should see this displayed and also the flowrate showing 0 M3/hr, so you might note these.
Also just shut the pump outlet valve for 10 secs or so with it running and the above numbers 5.9M/22kw/0.0M3/hr should remain the same.

 

[rcpilot]

Do the test again but shut all but one rad eg one problem one does that get hot ?

Hi well interesting results:- I turned off the rad in the sitting room (which is 2400mm x 600mm double panel) and left the kitchen one open and left the entrance rad open, the entrance rad started to get hot, the kitchen started to get hotter than before so turned that one off and the entrance rad got hotter, which means to me there is no airlocks, here's some info on the pipe work the entrance is on 10mm pipework the kitchen is on 8mm pipe work, the sitting room is on 15mm pipe work. Being a disabled pensioner (72) I am at my time of life not able to rip out the dead legs and increase the size of the pipe work, I could shut off the kitchen rad as the kitchen is open to the sitting room so the sitting room rad would warm up the kitchen, I could also put TRV's on the bathroom towel rails as they can get pretty hot and the room stat is in the sitting room ( a data term box) which means that when the bedrooms and the bathroom reached the desired temp they would close down resulting in an increased flow to the down stairs dead legs but probably not enough to heat up all the downstairs rads. As I have always maintained the pumps I selected to run my system are not suitable ( silly me) what do you think about using one of the commercial pumps that I listed, i can vividly remember years ago I did put a big pump in the system ( i suppose I could find out which one but it would take me a long time) I even had to manufacture a plate with rubber mountings for the vibration noise and special connection hoses to the system) it worked ok, that's all I can say, anyone want to buy a Grundfos Alpha 3b 15 50/60 bought 4 months ago and has only just started to be used (no heating over the summer months)

 

[rcpilot]

You are pumping practically NIL as you can see from the pump curve that the flowrate at 5.9M is 0.
The pump power is 22/23kw, you should see this displayed and also the flowrate showing 0 M3/hr, so you might note these.
Also just shut the pump outlet valve for 10 secs or so with it running and the above numbers 5.9M/22kw/0.0M3/hr should remain the same.

 

[John.g]

Have a careful look at the pump power as iis possible that its pumping 0.65m3/hr (10.8LPM), if so the pump power will be 34W so carefully note this and then briefly shut the pump outlet valve and again note the power.

 

[rcpilot]

so what's the answer, if you mean change the settings how do you do it (if you have read my last reply you should understand)

 

[John.g]

Just note the pump power as above "Have a careful look at the pump power as its possible that its pumping 0.65m3/hr (10.8LPM), if so the pump power will be 34W so carefully note this and then briefly shut the pump outlet valve and again note the power.

Even if you installed a 10M pump the flowrate (if any) will only increase by 30% (sqroot 10/6) so maybe from 10.8LPM to 14.0LPM, so checkout the power please.

Also if you only now changed to 100% CC from PP3 then the flowrate would only have been 7.9LPM at 3.15M. assuming the pump is running at 34w above.

 

[rcpilot]

Hi John thanks for your input, I need to shut down (my head is spinning from all that's going on) so as I told you I am getting on a bit, would it be possible to give me the settings for the pump so as to obtain the measurements you require, then I will shut the outlet down and record the settings again and we can take it from there thanks.

 

[John.g]

OK, (I'm getting on a good bit more than you).

Just put or leave the pump in CC (constant curve) mode at 100% which is the highest possible setting that will give the greatest circulation.

Leave what ever rads you have open to the circuit now and just start the boiler/pump and note the pump head in (meters) M, the flowrate in M3/hr and the most important one of all the power output in (watts) W. and then just shut the pump outlet valve for say 5 secs (boiler/pump running) and just note the above readings again, re open the pump outlet valve and if desired then shut down the boiler/pump. You may wish to post the first set of readings before doing the closed valve test.

 

[Ben-gee]

I’m fairly sure this is a balancing problem.

 

[rcpilot]

OK, (I'm getting on a good bit more than you).

Just put or leave the pump in CC (constant curve) mode at 100% which is the highest possible setting that will give the greatest circulation.

Leave what ever rads you have open to the circuit now and just start the boiler/pump and note the pump head in (meters) M, the flowrate in M3/hr and the most important one of all the power output in (watts) W. and then just shut the pump outlet valve for say 5 secs (boiler/pump running) and just note the above readings again, re open the pump outlet valve and if desired then shut down the boiler/pump. You may wish to post the first set of readings before doing the closed valve test.

OK, (I'm getting on a good bit more than you).

Just put or leave the pump in CC (constant curve) mode at 100% which is the highest possible setting that will give the greatest circulation.

Leave what ever rads you have open to the circuit now and just start the boiler/pump and note the pump head in (meters) M, the flowrate in M3/hr and the most important one of all the power output in (watts) W. and then just shut the pump outlet valve for say 5 secs (boiler/pump running) and just note the above readings again, re open the pump outlet valve and if desired then shut down the boiler/pump. You may wish to post the first set of readings before doing the closed valve test.

Hi thanks John I get tired very easily these days with the problems associated with me being diabetic and problems with my knees and arms, I never thought that having arthritis in my arms would feel like I had bad toothache but it does with me been to the dentist and he pointed this out to me, will talk with you tomorrow if that is ok with you, got to get this sorted out before the cold weather sets in as this is another problem with being diabetic I cannot stand the cold, never mind.