I want to improve my gravity fed hot water by adding a pump
- Thread starter simonaoz
- Start date
Sponsored Links
Just a follow up to earlier proposals.My intention is to install a Honeywell cyl stat(L641A1039) & a 22mm 2 port valve(V4043H with 5 wires---grey,brown.orange,blue,earth)My diemma is that i cannot figure out how to wire 2 pumps to work independently via a single live to the boiler.Does this require secondary switching at the interface between the pump lives and the live to the boiler to avoid both systems operating together.Also, i did a test today hoping to understand the switching arrangement(gravity to fully pumped) in the programmer.I expected that moving the switch over with the existing setup untouched that the CH circuit would be de activated,and that the HW circuit would function as normal on demand.Unfortunately,neither circuits were active.Would appreciate some help.Thanks
Ron
Ron
The system you describe is the Honeywell C-Plan (Pumped heating and Gravity Hot Water with Cylinder Stat and Valve) modified by adding a pump in the Hot Water return. D_Hailsham in his post on Jan 23 has included the wiring diagram for the C-Plan. If you add a pump to the Hot Water return, connect the pump live to Terminal 8, i.e the output from the Cylinder Stat. Pump Neutral and Earth are connected to Terminals 2 and 3 respectively.
IKM.
Thanks for response.I have just attempted to post a lengthy reply which has failed twice.Will try again later.
Ron
I have already done some prep work which includes some of your suggestions.The only difference is that i propose to connect the output @ terminal 8 to the brown of the 2 port zone valve & the black output to terminal 10 & to the 2nd pump.I now realise that my difficulties arose because i also intended to link terminal 10 to the boiler feed.This feed is currently from terminal 3 of the programmer(HW) & i proposed to connect it outside of the programmer directly to terminal 10.This clearly would have created difficulties of independence of the 2 pumps without additional switching to the boiler.However, i believe that by not linking terminal 10 directly to the boiler, i can make a common link to the boiler from terminals 3 & 4 of the programmer & maintain independence.That hopefully is the case if changing the link in the programmer from 'gravity' to 'fully pumped' gives independence to terminals 3 & 4.I tried to verify this a couple of days ago & didn't get an output @ terminal 3 on demand.That's my next job.Thanks for input.I have now verified that this switching is working as intended.
Thanks for response.I have just attempted to post a lengthy reply which has failed twice.Will try again later.
Ron
I have already done some prep work which includes some of your suggestions.The only difference is that i propose to connect the output @ terminal 8 to the brown of the 2 port zone valve & the black output to terminal 10 & to the 2nd pump.I now realise that my difficulties arose because i also intended to link terminal 10 to the boiler feed.This feed is currently from terminal 3 of the programmer(HW) & i proposed to connect it outside of the programmer directly to terminal 10.This clearly would have created difficulties of independence of the 2 pumps without additional switching to the boiler.However, i believe that by not linking terminal 10 directly to the boiler, i can make a common link to the boiler from terminals 3 & 4 of the programmer & maintain independence.That hopefully is the case if changing the link in the programmer from 'gravity' to 'fully pumped' gives independence to terminals 3 & 4.I tried to verify this a couple of days ago & didn't get an output @ terminal 3 on demand.That's my next job.Thanks for input.I have now verified that this switching is working as intended.
Sponsored Links
On reflection, i still cannot understand how the HW & CH circuits are each wired to provide separate power to the boiler. If they are fed from terminal 3 & terminal 4 of the programmer respectively to a commom link to the boiler,are they not dependant on the status of the room stat & cyl stat.If either of the stats are closed irrespective of the timer cycle will there not be a completed circuit to the 'other' circuit.I feel that i must be completely missing the point as i can only visuallise this setup being successfull by the inclusion of one way switches in both boiler circuits.Clearly no one has seen fit to do this.Please educate me on this.
I
ironman1
Depending on what type of controls you have a relay (RB1) may be in order to eliminate electrical backfeed , the other way would be to feed both pumps via brown wire @ motorised valve , considering pump over run is not an issue with you're boiler all is good.
Thanks for input ironman.
My postscript would be to enquire whether the room stat & cyl stat assume a neutral position or close after cycling to await the next timed demand.
My postscript would be to enquire whether the room stat & cyl stat assume a neutral position or close after cycling to await the next timed demand.
Ron,
It's difficult to comment on your system without knowing the full details of plumbing, controls and wiring. The common system for control of pumped heating and gravity hot water is the Honeywell C-Plan. You can download the leaflet with the wiring diagram here:
http://www.bssindustrial.com/supplier-literature/45/honeywell-sundial-plans.html
The C-Plan achieves independent control of the heating and hot water by means of the changeover switch inside the 28mm version of the Honeywell 2-port valve, i.e. V4043H1106. I note that the valve that you have is the 22mm version which has the single throw switch and is not suitable for a C-Plan system. You can download the V4043 leaflet here which should make the difference clear.
http://www.uk-plumbing.com/brochure/honeywell/V4043Datasheet.pdf
Maybe you have got the wrong valve because gravity hot water is usually 28mm or maybe 1" BSP for older systems.
If you follow the C-Plan wiring diagram through you can see that the heating and hot water can be controlled independently, i.e.
Heating:
The time controller outputs Mains Live to terminal 4 of the wiring centre. (The wiring centre is a plastic box containing a 10 way terminal block and has knockouts for cables.) The Room Stat is shown in the call for heat position and Live is connected to the heating pump via terminal 5, the wire link and terminal 9. Live is extended to the boiler via terminal 9 the normally closed side of the changeover switch in the valve and terminal 10.
Hot Water:
The time controller outputs Mains Live to terminal 6 of the wiring centre. The Cylinder Stat when closed i.e. calling for heat, connects Live to the valve motor via terminal 8. (The Cylinder Stat is shown in the Off position in the diagram). When the valve opens to allow gravity circulation in the hot water circuit it also moves the switch to the other position which connects Live to the boiler via terminals 1 and 10. The heating pump will only run if the Room Stat is calling for heat at the same time.
If you can get your system to the standard C-Plan you can improve the gravity circulation by fitting a pump in the hot water primary circuit and connecting the L, N and Earth wires to wiring centre terminals 8, 2 and 3 respectively. This is a non-standard modification but it has worked for me and others on this thread. You need to ensure that the feed and vent pipes are not blocked by the valve and/or pump.
It's difficult to comment on your system without knowing the full details of plumbing, controls and wiring. The common system for control of pumped heating and gravity hot water is the Honeywell C-Plan. You can download the leaflet with the wiring diagram here:
http://www.bssindustrial.com/supplier-literature/45/honeywell-sundial-plans.html
The C-Plan achieves independent control of the heating and hot water by means of the changeover switch inside the 28mm version of the Honeywell 2-port valve, i.e. V4043H1106. I note that the valve that you have is the 22mm version which has the single throw switch and is not suitable for a C-Plan system. You can download the V4043 leaflet here which should make the difference clear.
http://www.uk-plumbing.com/brochure/honeywell/V4043Datasheet.pdf
Maybe you have got the wrong valve because gravity hot water is usually 28mm or maybe 1" BSP for older systems.
If you follow the C-Plan wiring diagram through you can see that the heating and hot water can be controlled independently, i.e.
Heating:
The time controller outputs Mains Live to terminal 4 of the wiring centre. (The wiring centre is a plastic box containing a 10 way terminal block and has knockouts for cables.) The Room Stat is shown in the call for heat position and Live is connected to the heating pump via terminal 5, the wire link and terminal 9. Live is extended to the boiler via terminal 9 the normally closed side of the changeover switch in the valve and terminal 10.
Hot Water:
The time controller outputs Mains Live to terminal 6 of the wiring centre. The Cylinder Stat when closed i.e. calling for heat, connects Live to the valve motor via terminal 8. (The Cylinder Stat is shown in the Off position in the diagram). When the valve opens to allow gravity circulation in the hot water circuit it also moves the switch to the other position which connects Live to the boiler via terminals 1 and 10. The heating pump will only run if the Room Stat is calling for heat at the same time.
If you can get your system to the standard C-Plan you can improve the gravity circulation by fitting a pump in the hot water primary circuit and connecting the L, N and Earth wires to wiring centre terminals 8, 2 and 3 respectively. This is a non-standard modification but it has worked for me and others on this thread. You need to ensure that the feed and vent pipes are not blocked by the valve and/or pump.
IKM/Thanks for comprehensive posting.It will take some time to fully appreciate my next move.
This project was born because i need to replace the HW cylinder & the one supplied was for pumped systems only(22mm coil).I was advised by RM cylinders technical dept that this tank would not be capable of promoting gravity circulation & would induce air locks. I believe bona fide gravity tanks are only available to special order,and perhaps should be considered on the 'endangered ' list.
Based on the 2 pump option proferred by other contributors to the forum and because the pump has 22mm connections it seemed to me at the time that the motorised valve would only need to be 22mm.Whilst the current pipework is 28mm i note that the 'C' plan is a gravity HW system, and would not therefore be compatible with the new tank.
In view of the fact that other contributors claimed success with the 2 pump system and made no mention of possible electrical backfeed it seemed reasonable to proceed.I am unaware as to whether other contributors have full control of the HW&CH elements.Clearly this a hybrid proposal & does not fit the current convention.I am aware that in the longer term an update will be necessary.The only theoretical stumbling block to the original proposal that i can see, apart from some tuning/tweaking of the flow rates appears to me to be separation of the HW&CH outputs at the programmer to the boiler to eliminate possible electrical feedback and unsolicited pumping in either circuit.The inclusion of relays in the circuitry before the common boiler feed as proposed by Ironman seems feasible to me.Regretably, i'm no expert.Many thanks for your advice. Ron PS Having reviewed your posting thoroughly, you clearly were suggesting an assisted pumped HW system.
This project was born because i need to replace the HW cylinder & the one supplied was for pumped systems only(22mm coil).I was advised by RM cylinders technical dept that this tank would not be capable of promoting gravity circulation & would induce air locks. I believe bona fide gravity tanks are only available to special order,and perhaps should be considered on the 'endangered ' list.
Based on the 2 pump option proferred by other contributors to the forum and because the pump has 22mm connections it seemed to me at the time that the motorised valve would only need to be 22mm.Whilst the current pipework is 28mm i note that the 'C' plan is a gravity HW system, and would not therefore be compatible with the new tank.
In view of the fact that other contributors claimed success with the 2 pump system and made no mention of possible electrical backfeed it seemed reasonable to proceed.I am unaware as to whether other contributors have full control of the HW&CH elements.Clearly this a hybrid proposal & does not fit the current convention.I am aware that in the longer term an update will be necessary.The only theoretical stumbling block to the original proposal that i can see, apart from some tuning/tweaking of the flow rates appears to me to be separation of the HW&CH outputs at the programmer to the boiler to eliminate possible electrical feedback and unsolicited pumping in either circuit.The inclusion of relays in the circuitry before the common boiler feed as proposed by Ironman seems feasible to me.Regretably, i'm no expert.Many thanks for your advice. Ron PS Having reviewed your posting thoroughly, you clearly were suggesting an assisted pumped HW system.
when I did mine it was essential to use a 28mm 2-port valve because it has an output switch (it has an extra wire that the 22mm valve doesn't have)
I have forgotten most of the rest of it. You might be able to put a 28mm head on a 22mm body, I don't remember. Sadly the 28mm valves are a lot more expensive than the 22mm ones.
Or you could use a 3-port valve instead, and a single pump, but this might involve more re-piping which in my case would have been very awkward.
I am a householder not a pro.
p.s. you can put a 28mm valve on 22mm pipes using a special brass reducing cone in the compression fitting, which you can get at any plumbers merchant.
I have forgotten most of the rest of it. You might be able to put a 28mm head on a 22mm body, I don't remember. Sadly the 28mm valves are a lot more expensive than the 22mm ones.
Or you could use a 3-port valve instead, and a single pump, but this might involve more re-piping which in my case would have been very awkward.
I am a householder not a pro.
p.s. you can put a 28mm valve on 22mm pipes using a special brass reducing cone in the compression fitting, which you can get at any plumbers merchant.
Hi guys, sorry to wade in at the end and i've not read every single post but here goes!
If you use multiple pumps you also need to switch them with relays to prevent back feed. The voltage chain in your case would go...
Timer (HW) > cylinder stat > motorised valve > pump(HW)/boiler
Timer (CH) > room stat > pump(CH)/boiler
So... because the pumps/boiler/orange wire all need to be connected together you end up running the hot water pump with the 2-port valve closed.
It's important to realise that a 2-port valve is essentially a relay itself which seperates the voltages so you'd need to add one to the CH to do it properly. This is basically an S-plan or course.
Hope that helps
Andy
If you use multiple pumps you also need to switch them with relays to prevent back feed. The voltage chain in your case would go...
Timer (HW) > cylinder stat > motorised valve > pump(HW)/boiler
Timer (CH) > room stat > pump(CH)/boiler
So... because the pumps/boiler/orange wire all need to be connected together you end up running the hot water pump with the 2-port valve closed.
It's important to realise that a 2-port valve is essentially a relay itself which seperates the voltages so you'd need to add one to the CH to do it properly. This is basically an S-plan or course.
Hope that helps
Andy
I
ironman1
Ronswift...................................................................
Live feed from each pump can be fed via brown wire @ each respective motorised valve , this will have the pump energise whilst motorised valve is opening (no issues) , this will save on a relay along with the headache you 'may' encounter when wireing..............this will eliminate any backfeed from orange wires energiseing redundant circuit pump , considering the boiler does'nt require an overun facility then i say you're good to go.
...............i did mention this in my first post ..........................
Live feed from each pump can be fed via brown wire @ each respective motorised valve , this will have the pump energise whilst motorised valve is opening (no issues) , this will save on a relay along with the headache you 'may' encounter when wireing..............this will eliminate any backfeed from orange wires energiseing redundant circuit pump , considering the boiler does'nt require an overun facility then i say you're good to go.
...............i did mention this in my first post ..........................Thanks to all recent contributors,
Ironman/ There will only be one motorized valve conrolling the new HW pump.
Just to back refer to pipework in system.Glow worm back boiler/fire front( i know,antiquated, but bullet proof,for now,)28mm feed/return--vertical pipes in chimney, horizontal for 3metres at foor level & connection to HW tank.There are 4 connections @ the boiler.Does this render it unsuitable to be called a 'C' plan.Access to immediate boiler connections difficult.Access to vertical pipes requires fairly major building work?
It seems fairly clear to me know that the key is to aquire a 28mm motorised valve.If i can position it where i proposed to place the 22mm version then the theory becomes logical.ie on the short return immediately after leaving the HW coil alongside the new pump.The only other variable would be the connections at the programmer.The output for HW is terminal 3 and CH is from terminal 4.So presumably in the typical 'C' plan layout i should substitute (HW 3 for 6) &(CH 4 for 3)ie. that's if this hybrid can be aligned with 'C ' plan.Thanks again every one
Ron
Ironman/ There will only be one motorized valve conrolling the new HW pump.
Just to back refer to pipework in system.Glow worm back boiler/fire front( i know,antiquated, but bullet proof,for now,)28mm feed/return--vertical pipes in chimney, horizontal for 3metres at foor level & connection to HW tank.There are 4 connections @ the boiler.Does this render it unsuitable to be called a 'C' plan.Access to immediate boiler connections difficult.Access to vertical pipes requires fairly major building work?
It seems fairly clear to me know that the key is to aquire a 28mm motorised valve.If i can position it where i proposed to place the 22mm version then the theory becomes logical.ie on the short return immediately after leaving the HW coil alongside the new pump.The only other variable would be the connections at the programmer.The output for HW is terminal 3 and CH is from terminal 4.So presumably in the typical 'C' plan layout i should substitute (HW 3 for 6) &(CH 4 for 3)ie. that's if this hybrid can be aligned with 'C ' plan.Thanks again every one
Ron
A C-plan is having a 28mm 2 port on the coil return and one pump for the heating only. This would mean you have seperate time/temp controls for the heating and hot water but still have a gravity circuit to the cylinder.
You also need to take into consideration the feed and vent as I imagine they are currently on the cylinder coil and were never designed with a pump in mind.
As I understand it you're proposing to have the above C-plan but with a pump for the hot water also? This will not work unless you also add a 2-port valve or relay to control the CH pump.
Because the boiler is common to both demands you have a link that will bring on the CH pump when on hot water only.
Andy
You also need to take into consideration the feed and vent as I imagine they are currently on the cylinder coil and were never designed with a pump in mind.
As I understand it you're proposing to have the above C-plan but with a pump for the hot water also? This will not work unless you also add a 2-port valve or relay to control the CH pump.
Because the boiler is common to both demands you have a link that will bring on the CH pump when on hot water only.
Andy
Thanks Andy,
Aside from the wisdom of adding a 2nd pump to a system not designed for that purpose, which i understand has been successfully completed by other contributors can we refer to the wiring of the the 28mm 2 port valve.Bearing in mind my initial posting was regarding the concern of electrical back feeding which i fully accept would be a problem when using the 5 wire 2 port valve.Clearly this would require additional relay/relays.My understanding is that other contributors have achieved this circuit separation by using the 6 wire 28mm valve.I am no expert but am trying to follow a logical path.Understanding the internal switching in the 6 wire version seems to be the key.It seems to me that if the brown & orange link to form the HW circuit & white & orange link separately to complete the CH heating circuit, then independence would be achieved without the additional valve.Question is? How does the internal circuitry work.
Ron
Aside from the wisdom of adding a 2nd pump to a system not designed for that purpose, which i understand has been successfully completed by other contributors can we refer to the wiring of the the 28mm 2 port valve.Bearing in mind my initial posting was regarding the concern of electrical back feeding which i fully accept would be a problem when using the 5 wire 2 port valve.Clearly this would require additional relay/relays.My understanding is that other contributors have achieved this circuit separation by using the 6 wire 28mm valve.I am no expert but am trying to follow a logical path.Understanding the internal switching in the 6 wire version seems to be the key.It seems to me that if the brown & orange link to form the HW circuit & white & orange link separately to complete the CH heating circuit, then independence would be achieved without the additional valve.Question is? How does the internal circuitry work.
Ron
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
