central heating set up, zoning!! Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[martblue]

What we are looking for is a timer or programmer to do the following:

Domestic hot water gravity fed.


Central heating split into 2 zones,(upstairs & downstairs) each controlled by an 2 port zone valve with 4 wires.(brown, blue, orange, grey)

What we want it to do is:



1. To put boiler on for gravity domestic hot water
2. To have zone 1 Central heating on + domestic hot water
3. To have Zone 2 Central heating on + domestic hot water
4. To have both Zone 1 & 2 central heating on + domestic hot wate

We have no Room stats or tank stats so what type of timer/programmer do we want and do you have a wiring diagram for this set up.

We got a 3 zone one from horstmann but it was only anygood for a fully pumped system..

[ericmark]

I don’t see why any 3 channel programmer will not work? The valves must switch the central heating on not direct from programmer so with power to programmer and orange on valves at all times. And greys and hot water outlet from programmer all going to boiler. The programmer central heating outputs to brown wires on valves all neutrals and earths connected you should be able to switch on and off central heating and the hot water would be on all the time central heating is running plus when hot water is programmed. Am I missing something? Valve must of course control central heating it can’t be wired direct from programmer. Please explain why this should not work?

[martblue]

we got a 3 zone unit (horstmann)but wiring diagrams were all for a fully pumped system, we emailed them to see if there was a way we could use it but they just said it was for fully pumped system and as we have gravity for hot water it wont work, would mean putting pump on hot water and another valve, when all we want to achieve is to be able to zone upstairs and downstairs heating plus be able to put hot water on its own when needed..

[ericmark]

The C system is for gravity but that would not work in your case.

I have not wired in a zoned system like yours. But main problem is back feed where one output is latching on another.

As long as you use the built in switches on your zone valves this can be avoided.

I don't have details of the programmer you looked at but most programmers have a common input for internal clock and all output switches this means all outputs must be kept separate.

So by using each output to go to a motorised valve we can keep them separate. One output only can go direct to boiler.

But this is what you have. Three outputs work valve 1, valve 2, central heating boiler direct.

Then the valve internal switches also will put power to the boiler so the boiler will work when any valve is open or hot water is called for.

The problem is the pump which needs to run when valves are open but not with hot water.

This will require a relay as the type of valve fitted only has on/off switch.

If the valves work a relay and pump and the relay and hot water from programmer work boiler this will prevent back feed from hot water running pump.

[ericmark]

Until I tried to find a boxed relay I did not understand the problem. Theory is easy only when looking at practical side did I see the problem. The method in standard terms would use three motorised valves all with change over switches built in but the two you already have only have on/off switches. One can buy contactors which would do the job although expensive. To make a neat job would need you to make your own junction box with relay built in. So before I go into the how you must decide if you want to? Electrical it is easy it is the getting of an adaptable box, which will fit a relay and base then adding some terminal block ready to connect all the parts which becomes the problem. You would have needed a junction box anyway, the change is having one that would also fit a relay. So what do you want to do?

[martblue]

..cheers we are go to look into it, although we have been investigating it already.. might be a case of replacing zone valves with levers and doing it manually :( will let you know how we go..

[martblue]

will look into it, i think i will end up replacing zone valves with levers and control it manually.. :(
will let you know how we get on..
cheers..

[ericmark]

OK it of course has to be up to you. I did look as approx costs:-
MB Plastic Boxes
£2.58 to £7.99 unable to select size as no details on height of relay base.
Relay
Min 5A DPDT 240Vac N13AW £3.54
Size of Base 72 x 22.7mm (DPDT)
Height of body 30mm (DPDT)
8Pin Rly Skt DIN N36AW £1.98
L97AR 5A Term Block 3 Pk £3.29
What you want will work but of course a two gang switch that manually works the valves may suit just as well. I can't post links on this so if you were wanting more info I would need to hint at my web site on talktalk and then I can send diagram.
But anything non standard is a problem as if you ever ask some one to repair they have to use headology rather than following the set thing they do every day. So I am following the "C" plan for my fathers house even though I can do the same thing will less wires if I used my own design.

All best Eric

[martblue]

thanks for all your info, between myself and my dad we sat down and looked at this several times, and i think we have decided for simplicity this time, just going to use a normal programmer for ch & hot water, with lever valves for zoning the system when we want to, which after much chat might not happen to often but having the option is better than not..
will check out that site too,
cheers

[ericmark]

Much will depend on your boiler. If it has anti-cycle built in will work OK but without you may have problems. Also simple switches working motorised valves would be better than all work removing them. I found today CEF do sell din rail mount relays designed to fit consumer units but even if you did fit zone valves without a tank thermostat it will never be A1. With TRV's room stats no longer required but tank stats are or system cycles to check temp of hot water. Yes I know it would for central heating too but only when year just starting to get cold or just starting to get warm enough. assuming your boiler has variable output. If you used motorised valve on hot water with thermostat on tank it would be "C" plan by the way. All standard then.

[ericmark]

I have used Multi-sim to emulate the design and I see where I recommended a relay it just replaces the aux contacts that would exit in a motorized valve. I have put a diagram on web site if you can find it. www as always then same log in name as here on talktalk.net

[martblue]

cheers, have not had any luck with talktalk yet but wil keep trying.. :D

[ericmark]

Stage 1 fitting motorised valve completed on my fathers system. Using the change over contacts built into the valve to either supply the boiler from the pump when the valve is closed or from the live supply when the valve is open allows the running of the central heating without the pump. As yet Stage 2 fitting of tank thermostat still needs doing my father is making up his mind as to if to hard wire or use wireless version at extra £70 or so. But with hot water now only programmed twice a day it should reduce water temp and stop boiler cycling.
Step one all earths together and all neutrals together then live feed to Programmer and Grey depending on boiler you may also need to supply boiler. If so there will be another wire going into boiler to run boiler.
Step two out of Programmer via thermostats if used to pump for central heating and valve for hot water.
Step three valve white to pump and orange to boiler.
That is basic “Câ€

[ericmark]

I wonder if they will allow me to give you email address ericmark at talktalk.net then I can send you circuit diagrams well we shall see.

[Oliver_murphy]

there is no reason why a standard 2 channel programmer cannot control 2 heating zones.

All the programmer does in send a SwL down to a thermostat at a pre-programmed time. The stat then releys that live to the valve, and in turn to the boiler.

If you physically install two cable into the HEAT ON port in your programmer, then terminate those two cables into seperate stats, you will have effectavly zoned your system into upstairs and down.

Easy-peasy