3 zones 2 pumps 1 boiler

RJF

Hi lads, any suggestions as to the best way to wire a heating system with 3 zone valves, 2 pumps and 1 boiler using a 3 channel programmer. One pump is for hot water circuit with the other for heating 1 and 2 (one heating circuit, 2 zones). There is an auto bypass valve on hot water circuit. The problem is to prevent two pumps coming on together so that we have full interlock. I think I can do it with 2 contactors but am curious if any ideas out there.

ptogher14

Without looking at it is say it can be done with an 8 pin relay. One pump fed through a NO contact. One pump fed through a NC contact. Hence one pump can only ever come on

K.Flyer

Do you have thermostats for each zone valve?
Or are you straight off the clock to the pumps and zone valves?
What make / model boiler is it? (To determine switched live / volt free)

RJF

Sorry, ptogher, wont work because we need both pumps on when calling for heat and hot water together. It must be possible to turn on either pump individually or both together with the boiler coming on at the same time.

RJF

Hi KFlyer. It is a Super Q (Indoor Firebird, oil). The zones have stats but these don't matter as they are in series with the coil of the zone valves. The problem is when the grey (orange being permanent live) from the zone valve calls for heat we need to separate out which pump to turn on or not. Normally with 1 pump 1 boiler, if any of 3, or 2 of 3, or all 3 CALLS for heat, both boiler and pump turn on. What we need to get is

(1) Hot water CALL turning on HW pump (+boiler) only

or (2) Heating CALL turning on heating pump (+boiler) only

or (3) Heating and Hot water CALL turning on both pumps (+boiler)

Hope this makes sense. Thanks

RJF

This is how it would be wired with only 1 pump.

K.Flyer

Yes it can be done easily enough, I did something very similar recently on a vortex with 3 heat zones and a DHW (4 pumps) and no need for a relay. I will dig out my notes on it and try pm them to you later when I get a minute.

RJF

Thanks KFlyer. Do you recall if that was that with 4 pumps and 4 zone valves? There is no problem with just using the pumps on their own.

Calahonda52

I did this with 3 separate stats/clocks in 3 separate locations, and four zones, inc DHW, and one boiler pump.

I used four 11 pin relays, if KF has a non relay solution, great.
I tried it with an 8 pin first but didn't work, maybe it would but I like things simple and easy to follow.

One feature I added was a 4 gang switch after the timed output from each clock: this allows each zone to be shut down without going back to the clocks, so if going away and no/HW heat required, just shut off the 4 gang switch.

RJF

Thanks Calahonda. Could you explain why you needed a relay? I am presuming you used 3 single channel timeclocks such as APT or Immermat which would be equivalent to a 3 channel programmer. With only 1 pump and 1 boiler no relays should be needed or I might be reading you wrong? However in this case we 2 two pumps with 2 water circuits, 3 zone valves and 1 boiler as described earlier.

wilser

When the timeclock calls for heating use the live from this to fire the boiler and open the valve but use the grey/orange to start the pump.
Repeat for hot water.
Would that work?

K.Flyer

Sorry, late getting home.
The last time was a 3 zone clock > 3 stats > 4 modulating pumps + 4 zone valves > grey and orange switched live to boiler and no relays.
This was matching a new into old system which works perfectly now.
Looking at yours again with a quick sketch, you may need to go the relay route due to the two zones on the one pump. Care is needed in order to prevent latching and to have the pump on only when either heat zones are calling and for it to be off on HW only.
I will give it a bit more thought, but right now dinner beckons.

Calahonda52

RJF wrote: »

Thanks Calahonda. Could you explain why you needed a relay? I am presuming you used 3 single channel timeclocks such as APT or Immermat which would be equivalent to a 3 channel programmer. With only 1 pump and 1 boiler no relays should be needed or I might be reading you wrong? However in this case we 2 two pumps with 2 water circuits, 3 zone valves and 1 boiler as described earlier.

In layman language it was to stop the live getting to the other pumps once the first zone valve shut and completed that circuit, can't remember the colours but you know what I mean, one pair opens the valve and when it is open the other circuit is completed.

The three different stat/clock, I think are different than a 3 channel in so far as, in the diagram u sent, from memory, 10, 11, 12 for the two zone valves end up in a single connection point for each . this is not the same with the three stats/clocks as I have a 10,11,12 for each clock.
They are very simple, on off time wise and then if room temp is below required them it closes the circuit. None of this NO NC contacts etc stuff!!

I made it up c 20 years ago as an alternative to paying 1,000 quid for a system link.
For added fun, the 11 central rads in the house all have their own zone valve, with a 4 across by 3 down set of switches....
The other zones are for two big rooms forward and aft in the house and then the hot water.

As I said if KF cracks it without relays fine, if not PM me as I am not following this thread.

RJF

Afraid not, Wilser, both pumps would run when any ZV calls for heat. Also not proper interlock, boiler could continue firing with fault in ZV leading to possible overheating and high limit lockout.

K.Flyer

Would it be possible, do you have the space, to fit another pump so that each heat zone has its own pump?

wilser

RJF wrote: »

Afraid not, Wilser, both pumps would run when any ZV calls for heat. Also not proper interlock, boiler could continue firing with fault in ZV leading to possible overheating and high limit lockout.

Both pumps wouldn't run, only the pump which was connected to an open valve would run.
With regard to boiler firing and overheating the same will happen if pump seizes or doesn't run, regardless of which way you wire it.

RJF

Afraid not KF, I only found the second pump after cutting away the back of the cabinet for the kitchen drawers. Space is very limited. Barely able to get ZV's on.

K.Flyer

wilser wrote: »

Both pumps wouldn't run, only the pump which was connected to an open valve would run.
With regard to boiler firing and overheating the same will happen if pump seizes or doesn't run, regardless of which way you wire it.

Your way would work, but does not give true boiler interlock.

Simple set up would be Clock -> stat -> pump + zone valve -> grey and orange switched live to boiler.
Thats why I was asking if there was room to put a pump on each heat circuit. You do it this way and the stat kills the pump, shuts the valve, kills power to boiler. Stat calls for heat and away we go again.

RJF

Hi Wilser, thanks for the reply. I was thinking along the same lines initially but I think what happens is since all three lives from the 3 channels on the programmer would have to go to the boiler and this would feed back once one was on and turn on the other zone valves along with the 2nd pump. Its tricky to picture without diagrams.

RJF

Thanks again KF. The problem is caused because I have two pumps and 3 ZV's with no room for a third pump. If I used the clock-stat-pump solution I get caught with the 2 valves opening on the heating side when either one is turned on. The solution I am thinking on will use two 2 pole NO contactors. The grey from the HW will go to the coil on one contactor and the two greys from the heating to the coil on the other. Both will have permanent live and neutral on the input. The output on the HW will go to the HW pump and boiler. The output on the heating contactor will go to the heating pump and boiler. Any thoughts?

RJF

I just remembered I will also need to put in a pump over-run to deal with a hot system and all three ZV's closed. Some more fun facts on this system. Total of 18 rads- 12 on ZV1 and 6 on ZV2. Two rads on ZV1 are upstairs with other 10 downstairs. The 6 on ZV2 are upstairs. It was open system with 1/2" feed and exp pipe and also 1/2" vent to small tank which was virtually unreachable inside a hot press and up in peak of roof above large tank. Needed ladder to access upper door of hot press. Got rid of this-now sealed system. Copper cylinder also about 5 feet above floor. Will be putting stat on cylinder and on ZV1. Nothing on ZV2.

K.Flyer

P.m. sent

Dtp1979

Why not use 1 pump and zone the rest with motorised valves?

bluegas

Use two separate relays - connect the greys from heating zone valves to the first relay actuating coil and let it switch on the heating pump and boiler using separate contacts . The grey from the hot water zone valve will go to coil of second relay and this will switch on hot water pump and boiler using separate contacts .

RJF

Hi lads. Just home but got it sorted. I used two 2 pole NO contactors pretty much as I was thinking in post #20. Got full boiler interlock and no pumps running when they shouldn't be. Thanks for all your contributions. They helped me figure my way through it. However I will need to put in third contactor for pump overrun. I will try to post a wiring diagram over the weekend in case anyone's interested.

RJF

Hi lads, finally got around to doing a circuit diagram of my solution to the 3 zones, two pumps and one boiler problem in case anyone is interested. Comments or alternatives welcome.
Problem is - I now need to figure out how to add a pump overrun to this.
The sticking point is how to get the pump to run on its own without the boiler coming on also. And it has to be the HW pump only. I have a solution in mind and will post it when I get it finalized (hopefully). In the meantime any comments or suggestions welcome.
Hope the diagram is legible.

anthonyos

RJF wrote: »

Hi lads, finally got around to doing a circuit diagram of my solution to the 3 zones, two pumps and one boiler problem in case anyone is interested. Comments or alternatives welcome.
Problem is - I now need to figure out how to add a pump overrun to this.
The sticking point is how to get the pump to run on its own without the boiler coming on also. And it has to be the HW pump only. I have a solution in mind and will post it when I get it finalized (hopefully). In the meantime any comments or suggestions welcome.
Hope the diagram is legible.

Do you have any pictures of the job it be nice to see

RJF

No but I might be able to get some when I go back to do pump overrun, assuming I can figure out a solution. If so will post them.

Wearb

RJF wrote: »

Hi lads, finally got around to doing a circuit diagram of my solution to the 3 zones, two pumps and one boiler problem in case anyone is interested. Comments or alternatives welcome.
Problem is - I now need to figure out how to add a pump overrun to this.
The sticking point is how to get the pump to run on its own without the boiler coming on also. And it has to be the HW pump only. I have a solution in mind and will post it when I get it finalized (hopefully). In the meantime any comments or suggestions welcome.
Hope the diagram is legible.

You may need to use a relay to have the pump overrun without boiler coming on.

RJF

Thanks Wearb, I will explore that possibility. I can't see a way of doing it with another contactor or even 2 so I think relays are the next option.