Discuss Which is the more powerful pump? in the UK Plumbing Forum | Plumbing Advice area at PlumbersForums.net
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5.7 is a higher flow rate but might be the same pressure as the 3.8
Need more info
Need more info
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Are we taking heating or water and what’s the problem with the existing set up ?
Hi all well here is the problem in it's entirety, when we bought our house ( 2 bedroom ) up and down, the central heating was by way of a back boiler it had 3 radiators upstairs and 3 downstairs, but because of concrete floors downstairs, as it was previously council owned, the downstairs radiators were on what is known as dead legs. I put in a feature fireplace and ( as then you did not have to be gas safe ) I put a wall hung boiler in the bathroom and installed a fully pumped15mm pipe "Y" plan system which was open vented. The pump was a bog standard Grundfos one and as the boiler was getting long in the tooth I decided to get it replaced, in doing so I noticed that there was something wrong with the pump ie the body could be scraped with a knife and large chunks could be cut out of it so that was replaced with a new one. the chap who replaced the boiler put in a pressurised system. Not long afterwards I decided to take out the radiator in the bathroom and install a heated towel rail, now this was a big one, I noticed that the radiator in the entrance way was not getting hot at all but just left it . After a while I decided to get a Grundfos Alpha 2 L pump but it made no difference, so I then decided to get a Grundfos alpha 3b and take out the radiator in the sitting room and put in a big 2 panel one , for got to mention that I replaced all of the rads in the house with modern single panel ones the full length of the windows and put the bedroom ones on TRV's,. this is where everything went wrong, the Alpha 3b is setup and balanced using the 2 apps, Go Remote and Go Balance but these would not touch my system and could not balance it no matter what I did, I tried my best to manually balance the system, as I know how to, but that made no difference either, the entrance rad would not heat up the big one in the sitting room would not heat up the kitchen one would just get warm to the touch (these are all the rads on the dead legs) upstairs ones were getting quite warm, now I am left with the upstairs heating ok but nothing downstairs ( there are no air locks) I have come to the conclusion that the Alpha 3b is not powerful enough to pump the water round the system, I have spent quite a bit of time and money on pumps to try and rectify this problem but to no avail, so if any one out there knows of a powerful pump that can do the job drop me a line, one other thing I have come across is a Super 25 pump but it is a commercial one is there any reason why I cannot install it in my system obviously I would have to extend the port dimension as it is 180 mm not 130.
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a standard 15-60 eg ups2 or ups3 will be more than good enough for your system but it sounds like you have either a design issue or a blockage changing the pumpWon’t change much
Problem is it is the same design as before the only thing I have done is replaced the bathroom rad with a heated towel rail and replaced the flatpanel rad in the sitting room with a big double panel one, i know for certain that there is no blockage in the system because when I did the work I used the rad valves to get water down the dead legs on both sides of the rads before I connected then up.
Won’t change much
yep head in meters and the flowrate in M3/hr and power in watts and it is on proportional pressure
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It’s not a pump problem as it’s very unlikely you have two bad pumps out the gate
You sure it’s not a one pipe system?
You sure it’s not a one pipe system?
Give us the numbers then please , and the PP setting, should be a good indication of whats happening.
I'am not saying the pumps are bad, I am saying they are not powerful enough to pump the water round the system because of the dead legs, I am going to do an experiment tomorrow and will let you know the outcome
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Unless the dead legs are connected together which your system would never work these dead legs don’t matter as there just capped off services
Can you get any readings from the pump as it will reveal quite a lot IMO.
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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
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
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
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Do the test again but shut all but one rad eg one problem one does that get hot ?
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.
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)
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.
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.
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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.
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.
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.
Just to be clear
Pump definitely in CC3 mode and results with the pump outlet open were the same as with it closed, above, ie, 5.9M, flow rate 0.0m3/h, power output 22watts??, extraordinary as you are getting some circulation through the rads.
Also check that the pump inlet valve is fully open.
Just confirm the above please and I will have another look through the pump manual
Pump definitely in CC3 mode and results with the pump outlet open were the same as with it closed, above, ie, 5.9M, flow rate 0.0m3/h, power output 22watts??, extraordinary as you are getting some circulation through the rads.
Also check that the pump inlet valve is fully open.
Just confirm the above please and I will have another look through the pump manual
Yes John exactly the same, I had the same query how come the downstairs big radiator (upstairs closed) was heating up with a flow rate of 0.0m3/h dos'nt seem possible, the system is a sealed fully pumped "Y" plan
one
Doesn't seem possible, can you change to constant pressure mode CP3 which is a constant 4.5M, if not pumping in this mode then the power will read only 15W.
I did come across here sometime where a pump was displaying all the above symptoms but when the head was removed it was full of soft sludge with the impeller vanes choked, vanes can be cleaned with a tie wrap.
If its still not pumping on CP3, I would be inclined to isolate the pump and remove its head (2 or 4 stud bolts) complete with impeller and inspect it, then flush pump body ports alernatively tfrom he inlet and outlet valves, you will have to top up the boiler afterwards.
OR, if you still have the Alpha 2, simply install that and see will it pump, why did you replace it with the Alpha 3 as it has exactly the same performance but not the same amount of bells and whistles
If this pump was installed originally then you can look at this first for any signs of sludge inside, etc.
I did come across here sometime where a pump was displaying all the above symptoms but when the head was removed it was full of soft sludge with the impeller vanes choked, vanes can be cleaned with a tie wrap.
If its still not pumping on CP3, I would be inclined to isolate the pump and remove its head (2 or 4 stud bolts) complete with impeller and inspect it, then flush pump body ports alernatively tfrom he inlet and outlet valves, you will have to top up the boiler afterwards.
OR, if you still have the Alpha 2, simply install that and see will it pump, why did you replace it with the Alpha 3 as it has exactly the same performance but not the same amount of bells and whistles
If this pump was installed originally then you can look at this first for any signs of sludge inside, etc.
yes I have, another thing could my problems be associated with the outlet valve, why I say that is because the pump has the common connections on it but I have a gate valve just above it and I have been using that to close off the outlet and I have had problems with that type of gate valve before where the brass gate dose not fully open or fully close but sticks in one position.
Do you think that if I flushed out the whole system with a good cleaner it might do the trick?
i did notice you mentioned CP3, the pump was set in constant curve, so I reset it to CP3 closed the valve and the pump stopped, reopened it and the pump reset itself to constant curve, i have been using my wifes new phone but it keeps losing the connection with the pump and is very hard to reconnect
Yes, a prime suspect, its quite possibly closed now so if the threads arn,t stripped you should get 3 to 5 full turns anticlockwise from it , there's always a 1/2 to 3/4 of free play before they start to open or close.
Only as a very last resort IMO, get the pump working and we can see then if required.
If you do get it opened then leave it as Don,t require any more closed valve readings
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Ok John I will strip the Alpha3 out check the gate valve, if it is ok I will put the Alpha 2 back in to see if that makes any difference, will get back to you when it's done could be a few days, one thing I forgot to tell you is I suffer from a back problem, when I was working as a service engineer for a firm that serviced and repaired lifts,hoists cranes etc I fell off an overhead crane over in Carlisle many years ago and I back pain when i do too much
Hi john well striped the Alpha 3 out and guess what, both valves were barely open so that was the restriction to flow, I renewed some of the pipe work to one of the radiators because it had a service valve on it and it was leaking and I am now cleaning up after the work, if everything is hunky dory with the system what is the best setting for the Alpha 3 and I might try to balance it with the go balance app.
Ken
That's good news Ken, I would set it to CC3 to start with, if you have to close all the rad valves individually (no u/staors/d/stairs zoning), then just run it as is, ie, if d/stairs only opened up now just start the pump and post the numbers, you can then open up the u/stairs and run both systems together on CC3 and have a look at those numbers.
Don't know what the total rad(s) output is but assuming 20kw max then the flowrate required will be 20LPM (1.2M3/hr) at a rad dT of 14/15C/kw which would result in a pump head of 4.7M in CC3 mode, see what you come up with anyway and you can decide on balancing, if any, is required later.
My system, 12 rads, 20kw, no balancing, works fine at a 3.5M head.
Don't know what the total rad(s) output is but assuming 20kw max then the flowrate required will be 20LPM (1.2M3/hr) at a rad dT of 14/15C/kw which would result in a pump head of 4.7M in CC3 mode, see what you come up with anyway and you can decide on balancing, if any, is required later.
My system, 12 rads, 20kw, no balancing, works fine at a 3.5M head.
I have bled all the rads but left the kitchen one out of it for the time being, the bathroom towel rails are getting mad hot and the sitting room is starting to heat up, nothing yet in the bedrooms but I suppose balancing will bring them up
You said in post #1 that the upstairs rads were heating but not downstairs?,
If you have a Y system with a mid position valve then just carry out the basic check that the pump arrow is pointing towards it, also ensure that system is pressurized to 1.3/1.5 bar.
Can you also take pump values with DHW heating only on, then with (eventually) DHW+d/Stairs+U/stairs.
If you have a Y system with a mid position valve then just carry out the basic check that the pump arrow is pointing towards it, also ensure that system is pressurized to 1.3/1.5 bar.
Can you also take pump values with DHW heating only on, then with (eventually) DHW+d/Stairs+U/stairs.
Hi John, this flaming thing has got me demented, when I put everything back together, filled the system, bled the radiators, then started it up it was showing 24 watts on the pump and I think 0.6m3/h and the towel rads were getting mad hot the big rad downstairs was getting hot, both bedrooms were cold obviously because the lockshields were closed, the entrance rad was still cold, so I turned it off. Today I turned it back on and got the same results, so I started to manually balance the towel rails got them somewhere near the 12 deg difference checked the pump and the wattage had gone down to 15 and the m3/h was showing 0.0, hair now all over the floor.
Hi John decided to check the pump with the "go remote app" that pump has got a mind of it's own it reset itself from CC to CP so I reset it to CC and operating @ max it went back to showing 24 watts but the flow rate remained @ 0.0m3/h
Balancing should be the last thing to do IMO.
Can you just run on DHW and check values as this is practically a short circuit through the cylinder coil where most of the short? run will/should be in 22mm, if there is a balancing gate valve on the coil return, just open it fully.
I would expect to see ~ 34W on CC3.
Can you just run on DHW and check values as this is practically a short circuit through the cylinder coil where most of the short? run will/should be in 22mm, if there is a balancing gate valve on the coil return, just open it fully.
I would expect to see ~ 34W on CC3.
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