Which is the more powerful pump?

[rcpilot]

So, how many rads open d/stairs when all u/stairs rads + towel rads shut off when flow fell to zero??.
If you reopen just one towel rad does the flow increase?
Normally, even if only one rad open fully would expect a flowrate of - 0.3 m3/hrs and a pump power of - 25/26W on CC3.

Hi john there are 3 rads downstairs each one on it's own drop, when I shut off the bedroom rads there was no change to the wattage :- 34 and no change to the flow :- 0.6m3/h ( both valves on each towel rail were fully open) as soon as I touched either the lockshield or the on/off valve on either towel rail the wattage went down to 22 watts and the flow went down to 0.0 m3/h it's got me thinking that there is a problem with the pipework to or from the towel rails, if I have to alter the pipe work I can get at the flow from the "Y" plan valve and increase it to 22mm (it's 15mm at the present) and take it all the way into the bedroom to where the first drop is to the big rad in the sitting room then it would be 15mm after that as I cannot get at access after that

 

[rcpilot]

Hi john there are 3 rads downstairs each one on it's own drop, when I shut off the bedroom rads there was no change to the wattage :- 34 and no change to the flow :- 0.6m3/h ( both valves on each towel rail were fully open) as soon as I touched either the lockshield or the on/off valve on either towel rail the wattage went down to 22 watts and the flow went down to 0.0 m3/h it's got me thinking that there is a problem with the pipework to or from the towel rails, if I have to alter the pipe work I can get at the flow from the "Y" plan valve and increase it to 22mm (it's 15mm at the present) and take it all the way into the bedroom to where the first drop is to the big rad in the sitting room then it would be 15mm after that as I cannot get at access after that

I was just thinking that as the towel rails were fully open, and the bedroom rads closed and there was no change to the figures, as soon as I touched either valve on the towel rails I was virtually shutting off the flow because the pump cannot pump down the drops and back up again to the boiler, I don't know I might be clutching at straws

 

[John.g]

Looks that way alright, you my have both towel rads in series and the return tied back into the flow, a one pipe system in effect, if you run them again with both opened and the 3 d/stairs opened as well then the flow temperature into the 3 rad may be just lukewarm as it will/could be now the return temperature from both Towel rads?.

 

[rcpilot]

Looks that way alright, you my have both towel rads in series and the return tied back into the flow, a one pipe system in effect, if you run them again with both opened and the 3 d/stairs opened as well then the flow temperature into the 3 rad may be just lukewarm as it will/could be now the return temperature from both Towel rads?.

Hi John I have a few jobs to do to be able to lift part of the bathroom floor up again but as soon as I have had a chance I will get back to you with the outcome.

 

[rcpilot]

Hi John I have a few jobs to do to be able to lift part of the bathroom floor up again but as soon as I have had a chance I will get back to you with the outcome.

One thing John would 15mm piping have the same effect if so I am going to try and get most of the accessible runs redone in 22mm pipe and see if that improves the matter, will have to live in our caravan on the drive till I get it done.

 

[John.g]

15mm piping would require - 4.5 M head IMO to circulate 20LPM assuming total rad output of 20kw, if main pipework is 22Mm then a 2.5M head would probably suffice so see what the piping problem is first and you can decide then maybe to renew some sectios in 22mm but the 15mm is certainly not the cause of your present problem

 

[rcpilot]

15mm piping would require - 4.5 M head IMO to circulate 20LPM assuming total rad output of 20kw, if main pipework is 22Mm then a 2.5M head would probably suffice so see what the piping problem is first and you can decide then maybe to renew some sectios in 22mm but the 15mm is certainly not the cause of your present problem

Hi John, notice the time, I cannot sleep I am thinking constantly about this problem, thought of this, once I have checked the pipework for the 2 towel rails in the bathroom (that is where the problem lies I think) and done the necessary work, if I disconnect the heating pipe from the "Y" plan valve, blanked the valve off and put a drain hose on the heating pipe, isolated the pump so no water can come through the pump, the only way water can get into the boiler is through the filling loop, as the "Y" plan valve is blanked off no water can back flow through the hot water tank. If I then shut off all the flow valves on all the rads turn on the filling loop the boiler will fill up and the only way water can get to each rad is through the boiler via the return pipe, as all the flow valves are shut off the return pipe on each rad is now acting as a flow agreed so far? Now if I open the flow valve on the rad furthest from the boiler the water will flow through that rad and out of the drain hose I connected to the heating pipe I disconnected from the "Y" plan valve thus flushing out that rad and section of the heating system. If I then shut off that flow valve on that rad and opened the flow valve on the next furthest rad away from the boiler it will do the same as before. I can now do exactly the same for each rad until I get back to the nearest rad to the boiler, this will I hope ensure that there is no restriction in the pipework and also flushing the system out. If I then close the filling loop the pressure in the system should return to "0" as the drain pipe is still connected, if I disconnect the drain from the heating pipe the system should be filled to the height of the "Y" plan valve, so from that I can say that the downstairs would be filled and the upstairs filled to the height of the valve ie halfway up each upstairs rads, would you agree so far? I then reconnect the heating pipe to the "Y" plan valve and begin to fill up the system via the filling loop as all the rads are still shut off and the nearest rad to the boiler is open any air can only go to that rad so I vent it and then open up all the rads and fill them, having done all that the pump, as there should be no restrictions in the pipework, should be able to pump water through the whole system, if it cannot then I can assume the pump is not strong enough or I can put a stick of dynamite in the boiler and blow the whole thing to kingdom come I am that "P £ $ % & D off with the whole situation and go and live in our caravan in the back garden. I am ever so sorry for boring the pants off you and thank you very much for all the help you have given me, all the best Ken

 

[John.g]

I'll have a look at the above later on but you can see if pipework, (at least the main d/stairs flow/return) is free if you do the following before addressing the towel rad problems.

Shut off the upstairs, ensure all downstairs rads open fully, run the pump in the following 3 modes, CC3, CP1, CP2 &CP3 and note the pump values, then do the same tests with the two towel rads only and post your results, it will only take a few minutes to do these tests.

Also, please post the outputs (kw) or dimensions of the rads, including towel rads and their locations.

The main job is to fix your pipework and everything else can be decided then.

Edit, 3 modes are CC3, CP2 and CP3.

 

[John.g]

This might put your mind a bit more at ease until you actually see what's what.

I am assuming that there are two rads in series and in series then with the flow or return main piping, you would then have 4 very small valves in series which are designed only for flowrates sufficient for say a 3 kw rad, you can see below that the head loss is only 0.65M with a 3kw rad or 1.8M in the very unlikely event that you have a 5kw rad. With 2 rads in series the head loss is 3.6M @ 5kw/5LPM so if installed in the main flow/return then nothing left for pipeline losses etc.?.

So get your floor up ASAP.

 

[rcpilot]

This might put your mind a bit more at ease until you actually see what's what.

I am assuming that there are two rads in series and in series then with the flow or return main piping, you would then have 4 very small valves in series which are designed only for flowrates sufficient for say a 3 kw rad, you can see below that the head loss is only 0.65M with a 3kw rad or 1.8M in the very unlikely event that you have a 5kw rad. With 2 rads in series the head loss is 3.6M @ 5kw/5LPM so if installed in the main flow/return then nothing left for pipeline losses etc.?.

So get your floor up ASAP.

View attachment 77372

Hi john have checked all the pipework and everything seems to be ok in theory, there could be a "bit of a traffic jam" where the returns go back to the boiler but the only way I could alleviate that would be to incorporate swept "T"s in the return lines from the towel rails,

 

[rcpilot]

Hi John I have been a bit busy today but will do the tests tomorrow and get the results off to you also the kw of each of the rads

 

[John.g]

Hi John I have been a bit busy today but will do the tests tomorrow and get the results off to you also the kw of each of the rads

Very good, thanks.

Hi john have checked all the pipework and everything seems to be ok in theory, there could be a "bit of a traffic jam" where the returns go back to the boiler but the only way I could alleviate that would be to incorporate swept "T"s in the return lines from the towel rails,

The plot thickens!

Hi john there are 3 rads downstairs each one on it's own drop, when I shut off the bedroom rads there was no change to the wattage :- 34 and no change to the flow :- 0.6m3/h ( both valves on each towel rail were fully open) as soon as I touched either the lockshield or the on/off valve on either towel rail the wattage went down to 22 watts and the flow went down to 0.0 m3/h it's got me thinking that there is a problem with the pipework to or from the towel rails, if I have to alter the pipe work I can get at the flow from the "Y" plan valve and increase it to 22mm (it's 15mm at the present) and take it all the way into the bedroom to where the first drop is to the big rad in the sitting room then it would be 15mm after that as I cannot get at access after that

Can you verify/clarify the above.

With bedroom, Upstairs?,rads shut off, you get 34W/0.6m3/hr through the Towel rads + (maybe) the downstairs rads but if you close any one of the towel rads then 22W/0.0m3/hr.

Can or have you tried shutting the downstairs rads, opening the bedroom rads + the towel rads and note the values.
Then shut shut the towel rad(s) valves and note the values, ie with the bedroom rads only open.

Also can you see/show where the expansion vessel is tied in to the system.

A simple line diagram might show up something.

 

[rcpilot]

Very good, thanks.

The plot thickens!

Can you verify/clarify the above.

With bedroom, Upstairs?,rads shut off, you get 34W/0.6m3/hr through the Towel rads + (maybe) the downstairs rads but if you close any one of the towel rads then 22W/0.0m3/hr.

Can or have you tried shutting the downstairs rads, opening the bedroom rads + the towel rads and note the values.
Then shut shut the towel rad(s) valves and note the values, ie with the bedroom rads only open.

Also can you see/show where the expansion vessel is tied in to the system.

A simple line diagram might show up something.

Hi John I have made a line drawing of how the towel rails are plumbed into the system as you can see theoretically it is ok, where I have ringed the drawing could possibly be a "traffic jam back to the boiler" and as I said the only way to alleviate the problem would be to replace the "T" pieces with swept "T"s ?

 

[John.g]

Changing the Tees would make no difference IMO.
If you shut off the towel rad or rads does the front bedroom still heat up? and the other 2? bedrooms and what are the pump values?.

 

[rcpilot]

I'll have a look at the above later on but you can see if pipework, (at least the main d/stairs flow/return) is free if you do the following before addressing the towel rad problems.

Shut off the upstairs, ensure all downstairs rads open fully, run the pump in the following 3 modes, CC3, CP1, CP2 &CP3 and note the pump values, then do the same tests with the two towel rads only and post your results, it will only take a few minutes to do these tests.

Also, please post the outputs (kw) or dimensions of the rads, including towel rads and their locations.mm

The main job is to fix your pipework and everything else can be decided then.

Edit, 3 modes are CC3, CP2 and CP3.

Hi John here are the rad output wattages :- towel rail 1700 x 700mm 668w bathroom
towel rail 600 x 550mm 221w bathroom
flat panel 1800 x 500mm 752w front bedroom
flat panel 1500 x 500mm 626w back bedroom
flat panel 1100 x 500mm 459w entrance
flat panel 1100 x500 mm 459w kitchen
double panel 2400 x 600mm 4485w
the position on the system is as follows :- small towel rail 1
large towel rail 2
kitchen 3 :- on drop
entrance 4 :- on drop
front bedroom 5
back bedroom 6
sitting room 7 :- on drop

when the system was an open vented one it had the vent running up into the loft back to the filling tank, when the plumber put in the new boiler he cut the vent in the loft and attached the expansion vessel to it, pump values to come.