Central Heating Wiring

27061986a

Hi I was renting a house last year and the house had 4 central heating zones.
Zone 1 was for hot water, Zone 2 was for 1 part of downstairs, Zone 3 was for 2nd part of downstairs and Zone 4 was for upstairs. All the zones were switched from time clocks in the utility room. When zone 1 would be powered on then only the hot water would be heating; however if any of zones 2,3,4 were powered on then this would also turn on the hot water, you could see this as the light came on on the hot water switch (zone 1). This switch would even light up even if it was in the "off" position. How would this have been wired or what device/relay switch would have been used. I have attached drawing of timeclock setup.

2011

If properly wired only the zone selected should come on.

The issue you are having is that when one zone is selected it back feeds other zones. There are a number of ways of resolving this. One way is by using the auxiliary contacts on the zone valves to fire the boiler and another is by using relays.

27061986a

2011 wrote: »

If properly wired only the zone selected should come on.

The issue you are having is that when one zone is selected it back feeds other zones. There are a number of ways of resolving this. One way is by using the auxiliary contacts on the zone valves to fire the boiler and another is by using relays.

Thanks for the reply. How would this have been wired in the first place?

2011

27061986a wrote: »

Thanks for the reply. How would this have been wired in the first place?

Any one of a million different ways
Impossible to say but clearly not wired correctly.

Bruthal

2011 wrote: »

If properly wired only the zone selected should come on.

The issue you are having is that when one zone is selected it back feeds other zones. There are a number of ways of resolving this. One way is by using the auxiliary contacts on the zone valves to fire the boiler and another is by using relays.

Perhaps the question being asked is, how do you wire it, to get the hot water zone to heat, when any other zone(s) are on.

2011

Bruthal wrote: »

Perhaps the question being asked is, how do you wire it, to get the hot water zone to heat, when any other zone(s) are on.

Here is one way, this example is for 3 zones but the same logic could be followed for 4 zones:

Bruthal

Yes that is using the timeclock to bring on zone 3. The op seems to be asking how can it also be brought on whenever zone 1 and/or 2 are on.

Relay would do that. Obviously just using the timeclock can do it.

I have it setup with the sonoff relays, if I switch on the rads one, it also brings on the cylinder valve. If I switch on the cylinder one, it comes on alone.

The above diagram tends to use a pair of terminals from the boiler board, out to the aux connections, and return to the boiler board, rather than a feed from the spur. Often it is the same thing, but better practice to connect the pair of terminals in the boiler board to the motorized valve aux connections. Often it is in place of a link between the terminals in the boiler.

2011

Bruthal wrote: »

Yes that is using the timeclock to bring on zone 3. The op seems to be asking how can it also be brought on whenever zone 1 and/or 2 are on.

That is not the way I read it. I can't think why anyone would want to remove the option of being able to switch the hot water on or off independently of everything else. Anything short of this limits the options.

Relay would do that.

Yes, it would.

Bruthal

2011 wrote: »

That is not the way I read it. I can't think why anyone would want to remove the option of being able to switch the hot water on or off independently of everything else. Anything short of this limits the options.

I see it as the reverse.

Whenever a rads circuit is put on, the cylinder one comes on too.

That is what the op seems to be asking.

If the cylinder circuit is put on alone, as in summer, only it comes on. I have my setup like that.

2011

Bruthal wrote: »

That is what the op seems to be asking.

Maybe, but ultimately that leaves the end user with less options

Bruthal

2011 wrote: »

Maybe, but ultimately that leaves the end user with less options

Well I myself dont see a major loss of options if heating rads also heats the cylinder, and its easy to set it up as an on off option. But it depends on the user, the setup of the installation etc.

27061986a

What type of relay could you use for this setup and also how would it be wired?

Cerco

I think there is some merit in the way the system was configured, albeit the method could be investigated for safety, compliance etc.
So you have a situation where the water can be heated independently of the space heating , as should be in (ideal) summertime.
So if you switch on space heating, in any or all zones, you also have water heating also. It seems logical to me that if you need space heating then you also need hot water.
From a technical perspective you do not have zone isolation but from a practical perspective it seems to me ideal.

2011

Cerco wrote: »

It seems logical to me that if you need space heating then you also need hot water.

Without exception?

Normally when I arrive home in the evening after work I would not want hot water as I shower in the mornings. So I normally don’t have a need to heat water in the evenings. Maybe this is just me

If you come home and the house is freezing the quickest way to heat an area is just to switch on the zone for that area and heat nothing else.

Bruthal

Very easy to setup that the hot water coming on with other zones as selectable.

2011

+1

It’s only a minor detail.

Cerco

2011 wrote: »

Without exception?

Normally when I arrive home in the evening after work I would not want hot water as I shower in the mornings. So I normally don’t have a need to heat water in the evenings. Maybe this is just me

If you come home and the house is freezing the quickest way to heat an area is just to switch on the zone for that area and heat nothing else.

No, not without exception as you mention but I think a majority, maybe a small one, would want hot water in the evening also.
Simple / older heating systems use the configuration described with two zones:
1. Hot water only
2. Heating & hot water. :(no option for heating only)
I suppose the need for hot water is mitigated by the prevalence of kitchen appliances, dish washers etc. If you have a well insulated hot water tank then the heat loss during the day will be replenished quickly, unless you empty the tank in the morning with power showers. The OP’s configuration allows space heating isolation albeit it hot water, so you could heat one room along with the tank. I guess it is a matter of personal choice.

2011

Cerco wrote: »

No, not without exception as you mention but I think a majority, maybe a small one, would want hot water in the evening also.

Agreed.

I suppose the need for hot water is mitigated by the prevalence of kitchen appliances, dish washers etc.

Exactly.

If you have a well insulated hot water tank then the heat loss during the day will be replenished quickly, unless you empty the tank in the morning with power showers.

Agreed.

However for maximum efficiency it is best to heat water as it is required or just before hand as this will reduce heat loss. How much of a difference this will make depends on a large degree on the quality of the tank insulation.

In my situation the tank is left cold in the am following showers.

Wearb

I have mine plumbed with only 2 zones ( I could easily add DHW only). I haven't added it because:
1. I have a well insulated cylinder.
2. I've an oil boiler and PRV's (TRV). Sometimes there will only be a call for heat from a rad or two. I believe that the inclusion of the cylinder -in that instance- works as a sort of thermal flywheel (sorry but can't think of the correct phrase right now) and reduces oil boiler cycling. I have monitored it with and without cylinder included. With cylinder included, the circulating pump runs for much longer before the boiler kicks in.

2011

Fair point, I guess essentially the hot water tank provides thermal inertia / momentum.