Which is the more powerful pump?

[rcpilot]

Hi all just picking your brains 2 pumps with flow rates of 3.8 and 5.7 which is the more powerful, also can you fit a commercial pump into a domestic system?

 

[John.g]

It's amazing how the flow drops off with both T.rads shut, would wonder if any problem with system pressure...EV pipe blockage etc but as system was refilled using this then? You might just increase pressure by topping up to 1.5bar.
The pumps appear to be the same so probably OK to swap heads, but as you can easily isolate maybe easier to swap whole pump?

 

[rcpilot]

It's amazing how the flow drops off with both T.rads shut, would wonder if any problem with system pressure...EV pipe blockage etc but as system was refilled using this then? You might just increase pressure by topping up to 1.5bar.
The pumps appear to be the same so probably OK to swap heads, but as you can easily isolate maybe easier to swap whole pump?

what would be the max pressure I could use on this system/ easier for me to just unbolt 4 bolts and swap heads

 

[John.g]

The boiler PRV lifts at 3bar so wouldn't,t pressurised to move than 1.5/1.7 to avoid lifting it when system heats up. Changing pump heads only gives you a opportunity to inspect impellers for sludge build up.

 

[rcpilot]

The boiler PRV lifts at 3bar so wouldn't,t pressurised to move than 1.5/1.7 to avoid lifting it when system heats up. Changing pump heads only gives you a opportunity to inspect impellers for sludge build up.

Hi john the system used to heat up no bother with the old bathroom rad and the smaller sitting room rad so I have eliminated both of them by closing them off, if the problem was with those two items then the system should now heat up with no problems unless there is an airlock somewhere and the only way I would be able to say for definite would be to carry out flushing the system section by section, if no airlock was present then the only solution is the Alpha 3 is not doing what it is supposed to do, I can change the heads but I would not be able to say the Alpha 2 was in a working condition, but if the system heated up then it's proof the Alpha 3 is cattle trucked agreed?

 

[John.g]

Yes, go for that, should be a simple task, back flush from both sides when pump head removed but keep system topped up and to 1.5bar finally.

 

[rcpilot]

Yes, go for that, should be a simple task, back flush from both sides when pump head removed but keep system topped up and to 1.5bar finally.

will let you know how I get on

 

[rcpilot]

will let you know how I get on

I removed the heads from both of the pumps and the size of the impellers are totally different, the Alpha 3 is only 38mm in dia where as the Alpha 2 is 63mm in dia so I am going to have to swap over the whole pumps

 

[rcpilot]

I removed the heads from both of the pumps and the size of the impellers are totally different, the Alpha 3 is only 38mm in dia where as the Alpha 2 is 63mm in dia so I am going to have to swap over the whole pumps

Hi John I changed the pumps over and put the Alpha 2 on it's highest setting, there was no difference which makes me think (as I have not done the flushing yet) there is a blockage in the pipe line, I put my thinking cap on and came up with this, the picture that is in the attachments of the towel rail plumbing, as the towel rails were off, the system was acting as before so I opened the small towel rail and it started to get hot in no time at all, so I concluded that the flow and return for that towel rail was ok, the same applies to the large towel rail, but when I turn the towel rails off the system goes back to where it was before so I am thinking the blockage could be where the return from the front bedroom meets the return to the boiler any ideas?

 

[Ben-gee]

Investigate that area of pipework with a magnet, if it’s attracted then chances are it’s full of steel based sludge.

 

[rcpilot]

Hi John I changed the pumps over and put the Alpha 2 on it's highest setting, there was no difference which makes me think (as I have not done the flushing yet) there is a blockage in the pipe line, I put my thinking cap on and came up with this, the picture that is in the attachments of the towel rail plumbing, as the towel rails were off, the system was acting as before so I opened the small towel rail and it started to get hot in no time at all, so I concluded that the flow and return for that towel rail was ok, the same applies to the large towel rail, but when I turn the towel rails off the system goes back to where it was before so I am thinking the blockage could be where the return from the front bedroom meets the return to the boiler any ideas?

Hi John, well I cut out the "T" piece I thought might be the problem but it was ok , what was left now was an open return that was connected to that "T" so I connected a drain pipe to it, one end that was open that went to a towel rail I blanked that off, the other open end went to the boiler so I blanked that end off so I started to flush the system using the filler - expansion tank as the flow the water went through the boiler past the "Y" plan valve and into the flow pipe opened up each rad in turn and got a flow in was not very strong in fact I could stop it by putting a finger on the end of the return drain pipe, I flushed out each section in turn by opening and closing the return valves on each rad, got exactly the same flow through each section, I am going to try and put mains water pressure through the flow, by eliminating the expansion tank, boiler and "Y" plan valve and should get mains pressure back out of the return drain pipe if I do then it is as I said at the start the pumps that I have are not strong enough for my system or they are both knackered which means I need a stronger pump any ideas on these :- Britherm SL 25-80/180, Brithem super 25-120/180, Britherm Pro 2580/180, yes I know the port to port is 180 mm but that is easily overcome.

 

[John.g]

Sorry for late reply, didn't get any email notification(s) of your posts.
Will read the above in more detail later.

You have a sealed system so you will have the same pressure throughout the system and it will be at the EV pressure (with allowance for elevation) so if you were to attach a pressure gauge to any part of the system then you should get 1 to 1.5bar?? pressure, makes me wonder (again) where it joins the system exactly. Unless the system is 100% blocked in places then you should feel that pressure if you hold your finger over any point of opening, if there is a blockage then yes the flow will reduce to a trickle once you remove your finger.
When you were testing/flushing, how did you keep the EV pressure at 1/1.5bar?. also whether flushing with the EV or mains, ( not a bad idea), ensure the 3 port valve is, preferably latched in CH position but if not, latch it in mid position.

I would be very surprised if any one of those two pumps is knackered, if the impellers/pump ports are clear and you are getting the power associated with the mode settings and flows, and you were, then nothing wrong there IMO.

Where does the EV outlet join the system, is it before the pump?, you might remove it where it joins the system and ensure clear.

 

[rcpilot]

Sorry for late reply, didn't get any email notification(s) of your posts.
Will read the above in more detail later.

You have a sealed system so you will have the same pressure throughout the system and it will be at the EV pressure (with allowance for elevation) so if you were to attach a pressure gauge to any part of the system then you should get 1 to 1.5bar?? pressure, makes me wonder (again) where it joins the system exactly. Unless the system is 100% blocked in places then you should feel that pressure if you hold your finger over any point of opening, if there is a blockage then yes the flow will reduce to a trickle once you remove your finger.
When you were testing/flushing, how did you keep the EV pressure at 1/1.5bar?. also whether flushing with the EV or mains, ( not a bad idea), ensure the 3 port valve is, preferably latched in CH position but if not, latch it in mid position.

I would be very surprised if any one of those two pumps is knackered, if the impellers/pump ports are clear and you are getting the power associated with the mode settings and flows, and you were, then nothing wrong there IMO.

Where does the EV outlet join the system, is it before the pump?, you might remove it where it joins the system and ensure clear.

Hi john thanks for the reply, lets start from the beginning, I bought the Alpha 2 a few years ago when I found out there was something wrong with the basic Grundfos pump, after it was fitted it was working ok, then aprox 5 years ago we replaced the old boiler with the Worcester 15 Ri again everything was fine until last year when I put in the heated towel rails, I then thought that there was something wrong with the Alpha 2 pump so I bought the Alpha 3 but that did not solve the problem, as we have tested the system thoroughly and by eliminating the towel rails the system should have heated up the same as the towel rails but it did not, I think buying a new pump at this stage is not the answer because if the system was clear the Alpha 3 should have maintained 34w and 0.6m3/h at least but it did not it went back to 22w and 0.0m3/h and the system barely got warm, so I am thinking there is a partial blockage somewhere and I think, but I could be wrong, that it is in either the flow or return between the towel rails and the first real radiator which is the kitchen because if it was past the kitchen or for that matter before the front bedroom, the kitchen rad should have got hot and the entrance but they do not, the entrance does not heat up at all, so I am going to rod the flow and return and see what happens, if they are clear then I think it is a new pump

 

[John.g]

Can you just do up another line diagram just on that circuit including the rads, pump, 3 way valve & expansion vessel etc.
If the lines are clear then I would be almost 100% sure that a higher head pump will not sort the problem, we know (proved) that the Alpha 3 has a 6.4M head available and pumps 0.6m3/hr at this head, a 8M pump would increase the 0.6m3/hr flow to 0.67m3/hr and a 10M pump will increase the flow from 0.6m3/hr to 0.75m3/hr but neither can increase or get anything to flow where you have zero flow with a 6.4M pump head?.

 

[rcpilot]

Can you just do up another line diagram just on that circuit including the rads, pump, 3 way valve & expansion vessel etc.
If the lines are clear then I would be almost 100% sure that a higher head pump will not sort the problem, we know (proved) that the Alpha 3 has a 6.4M head available and pumps 0.6m3/hr at this head, a 8M pump would increase the 0.6m3/hr flow to 0.67m3/hr and a 10M pump will increase the flow from 0.6m3/hr to 0.75m3/hr but neither can increase or get anything to flow where you have zero flow with a 6.4M pump head?.

Hi john the line drawing is in the attachment and my way of thinking if there was a restriction in the flow after the "Y" plan valve any radiator that was prior to that restriction would heat up normally, if there was any restriction in the return line any radiator that was prior to that restriction would heat up normally, as the towel rails are both heating up and the rest of the system is just warming up or not getting warm the restriction if it was in the flow is between the towel rails and the kitchen, if it was in the return again the restriction would be between the towel rails and the kitchen, what do you think?

 

[John.g]

That's great Ken, one picture is worth a thousand words.
From your post #80

All Rads ON 0.6m3/hr 34W
Large T.Rad Hot
Small T.rad Hot
Back B.room Hot
Front B.room L.warm
Entrance Cold
Sitting Room Cold
Kitchen Just Off Cold

Small T.rad Off, remaining Rads ON 0.4m3/hr 32W
Large T.Rad Hot
Small T.rad Off
Back B.room Hot
Front B.room L.warm
Entrance Cold
Sitting Room Cold
Kitchen Just Off Cold

Bothl T.rads Off, remaining Rads ON 0.0m3/hr 22W
Large T.Rad Off
Small T.rad Off
Back B.room warming up
Front B.room warming up
Entrance Cold
Sitting Room just about warming up
Kitchen Just about warming up

What strikes me straight away is the back bedroom, It stays Hot in the first two cases and is heating up with both T.rads off but with apparently no pump flow.
If its getting hot then that sort of proves that there is a flow through the main flow/return circuits? Can you try that Back B.room rad on only and see the pump values, if any?,

Are you sure that the isol valves on the 3 "cold" rads, Kitchen, Entrance and sitting room, are fully opened?

Flushing everywhere you can with the mains is about the most logical step now.

Your observations re restrictions make sense so running the back b.room on its own just might tell something.

 

[rcpilot]

That's great Ken, one picture is worth a thousand words.
From your post #80

All Rads ON 0.6m3/hr 34W
Large T.Rad Hot
Small T.rad Hot
Back B.room Hot
Front B.room L.warm
Entrance Cold
Sitting Room Cold
Kitchen Just Off Cold

Small T.rad Off, remaining Rads ON 0.4m3/hr 32W
Large T.Rad Hot
Small T.rad Off
Back B.room Hot
Front B.room L.warm
Entrance Cold
Sitting Room Cold
Kitchen Just Off Cold

Bothl T.rads Off, remaining Rads ON 0.0m3/hr 22W
Large T.Rad Off
Small T.rad Off
Back B.room warming up
Front B.room warming up
Entrance Cold
Sitting Room just about warming up
Kitchen Just about warming up

What strikes me straight away is the back bedroom, It stays Hot in the first two cases and is heating up with both T.rads off but with apparently no pump flow.
If its getting hot then that sort of proves that there is a flow through the main flow/return circuits? Can you try that Back B.room rad on only and see the pump values, if any?,

Are you sure that the isol valves on the 3 "cold" rads, Kitchen, Entrance and sitting room, are fully opened?

Flushing everywhere you can with the mains is about the most logical step now.

View attachment 77437

Hi john put mains pressure to the flow after disconnection from the "Y" plan valve thus eliminating pump, boiler, "Y"plan valve and domestic hot tank, both towel rails shut off from flow, only kitchen rad fully open did get flow but as the piping to that rad is 8mm bore got a reduced flow but i would have thought that if mains pressure was going through it the water would have squirted out but it did not could stop it with light finger pressure, so I opened the back bedroom so only kitchen and back bedroom fully open flow increased but not to what I would have expected could stop it with finger pressure, which makes me think that there is a restriction somewhere in the system, to my thinking as before between towel rails and kitchen whether it's in the flow or return needs investigation, I am going to try and rod the flow and return with welding rods joined together, see what happens.

 

[John.g]

You certainly shouldn't be able to plug any opening with your finger doesn't matter how restricted the pipe is as the pressure will build up regardless? assuming mains pressure.

Maybe prove main piping clear first by breaking the return at the boiler and flushing through, then measure into a bucket for 30 secs or so to get the LPM, by making a educated guess at the mains pressure then can see if flowrate is ok for x meters of 15mm piping?.

 

[rcpilot]

You certainly shouldn't be able to plug any opening with your finger doesn't matter how restricted the pipe is as the pressure will build up regardless? assuming mains pressure.

Maybe prove main piping clear first by breaking the return at the boiler and flushing through, then measure into a bucket for 30 secs or so to get the LPM, by making a educated guess at the mains pressure then can see if flowrate is ok for x meters of 15mm piping?.

At this moment I think I have made some progress, as I said I was going to rod the pipework with 1/8 gas welding rods soldered together with a length of aprox 12-15 foot, I rodded the return which I had previously cut nothing going on there, I then cut the flow and the rod went in so far and I felt a bit of resistance so I pushed and fed the rod in further and used an in and out motion till it felt quite easy, then I connected the mains to the return opened up the furthest rad from the boiler connected a drain to the flow so that if there was anything in the system it would not flow round the system but out of the flow into the shower tray, you should have seen the amount of hard lumps of magnetite that came out, I am going to rod it again and see if any more comes out once it is clear I will reinstate the pipe work and try it, if all is clear or much improved I am thinking of getting it power flushed then fitting a magnaclean.

 

[rcpilot]

At this moment I think I have made some progress, as I said I was going to rod the pipework with 1/8 gas welding rods soldered together with a length of aprox 12-15 foot, I rodded the return which I had previously cut nothing going on there, I then cut the flow and the rod went in so far and I felt a bit of resistance so I pushed and fed the rod in further and used an in and out motion till it felt quite easy, then I connected the mains to the return opened up the furthest rad from the boiler connected a drain to the flow so that if there was anything in the system it would not flow round the system but out of the flow into the shower tray, you should have seen the amount of hard lumps of magnetite that came out, I am going to rod it again and see if any more comes out once it is clear I will reinstate the pipe work and try it, if all is clear or much improved I am thinking of getting it power flushed then fitting a magnaclean.

Hi John HURRAY sorted the rads are getting hot now just goes to show magnetite the root of all evils, rodded the flow for the second time and got a lot more out, I am going to get the system power flushed after we come back from our hols, then I am going to fit a magnaclean, obviously the heating will get better once I have balanced it, it still has the Alpha 2 pump in it, I will keep the Alpha 3 as a spare.
Thanks for all your help much appreciated
All the best Ken

 

[John.g]

Excellent news, I will have a few extra drops of Jamesons tonight not to mention a rake of Guinness.

Does the Alpha 2 display values as well?, W (watts) will do fine. If so, when you get a chance you might run it on CP2 which is 3M and post the values, or/and any values you have just now, that will give a very good indication of how clean the system is.

What exactly does a power wash achieve that you havn't already achieved, or how does it work??. you can flush out each rad individually in your own time and add inhibitor when all is done.