Heating programmer wiring

Daragh86

I'm confused by the set up of heating programmers. I'm installing a combi gas boiler which has a built in 24 hour analogue timer. I'm hopefully going to bypass the analogue timer and hook it up to a 7 day programmer which will controle two heating zones - upstairs and downstairs.

In the two heating zones I'll have a wireless room stat in each and TRVs on all the other radiators in each zone.

I'm confused though as to how the system works and what should be wired to where...??? If somebody could help me out so that I understand the system before I buy it all and get someone to install it that'd be great.

This is what I reckon happens so if somebody could confirm it or put me in the right direction I'd appreciate it. The motorised valves for each of the two zones are wiring to the reciever of the wireless room stats? Then the stats are wired to the heating programmer which is then wired back into the boiler?

I'm also confused by what controles the turning on and off of the boiler if both motorised valves close due to the room stats reaching the desired temp? Is this done from the heating programmer which recieves the signal from the room stat?

Thanks for any help in advance.

I wouldn't bother trying to get my head round it if i was you as a little bit of information can leave you with a headache, what your are asking for is basic and any installer/electrician should have no problem setting this up for you, if you are determined to know, then with the boiler will be the manufactures instruction which will lay out the wiring requirements for that particular boiler and any links for external controls, some of these links are low voltage and this would have to be checked for compatibility, the manuals tend to show the wiring set up you are looking for so it's the best place to start, also if you want to confirm anything before buying then download the manual from the internet or ring the manufactures who will give you the heads up, all due respect if you don't get the basic wiring requirements then i would trust your installer as you could just end up more confused, Gary.

M cebee

the timer and stats can operate the valves

the contacts on the the valves or logic strips etc. can then fire the boiler or call for heat

either someone can design the 'heating system' or for smaller jobs sometimes the plumber tells the sparkie how he wants it to work
and the sparkie wires it accordingly

Daragh86

Thanks for the help.

I've had a look at a couple different programmers, boilers, etc to see the different wiring types. I've come across a Honeywell ST9500C 2 channel programmer which is designed for two heating zones. The wiring on this programmer is programmer to stats to motorised valves to boiler which makes sense to me.

Only problem now is that the boiler I've chosen has an analogue timer built in and I can't seem to find any wiring diagrams to suit this situation, I just want to make sure that it is possible to run the system before I buy everything (a friend of mine is installing it for me and I don't want to be bothering him too much with going out and buying the stuff for me as well). Anybody know if this can be done and if so where I might find some info on it? Thanks.

Oh and also - anybody know where I might pick up the Honeywell ST9500C programmer or maybe a place that will order it in for me? Thanks.

M cebee

the boiler should have a switch( 24hr/timed.)

you prob set it to 24hr when your doing your own timing

get someone competent to look after the job .best way

eoghan.geraghty

Daragh if your friend is wiring it, I'd let him get the stuff.
I hate it when I go to do a job for a friend and they've picked up the wrong gear, it invariably happens and it costs me more time and frustration working with it.
Using the inbuilt analogue programmer should cause no problem, just make sure he uses the inbuilt link in most modern HE boilers.

2011

There is a good wiring diagram and explanation here:

http://boards.ie/vbulletin/showpost.php?p=57759046&postcount=6

The only place to look is in the manufactures instructions which will cover all the requirements for the electrics, in saying that you probably wont find anything with the boiler clock removed as it designed to be there, don't remove the clock or attempt to redo the boiler clock wiring unless it's in the manual, as this can effect your warranty, as above leave the boiler clock in the constant position so the clock will have no impact.

The things you need to be concerned about would be to make sure the boiler has a permanent live feed via a fused spur within arms reach of the boiler, also that it has a link for external controls and what voltage it is looking for as some boilers can be damaged if you bring 240v to the link, again without sounding like a stuck record:eek: read the boiler manual, it will tell you everything you need to know about all aspects of the installation, Gary.

2011

2011 wrote: »

There is a good wiring diagram and explanation here:

http://boards.ie/vbulletin/showpost.php?p=57759046&postcount=6

Without going all boiler nerdy:), i wouldn't advise that design with a gas boiler with a link for external controls, the reason is it's good working practice(and i don't see it often) to bring back to the link what ever originated on the other side of it after it's gone via external controls, the boiler could be low voltage/no voltage switching or more importantly some boilers cut the power going out on the first part of the link if a safety device kicks in, so if there is a moody power coming back to the boiler then the safety devices have been bypassed and the boiler can still fire which can lead to death or injury, which has happened in the past, Gary.

Daragh86

Thanks for all the help lads, I think I understand it all now. I like to know all I can about this kind of thing if it's going to be in my house.

Most importantly I shouldn't cut the red...no no, the blue...

eoghan.geraghty

2011 wrote: »

There is a good wiring diagram and explanation here:

http://boards.ie/vbulletin/showpost.php?p=57759046&postcount=6

I'd agree with gary71 here.
That's the original way of wiring heating control systems, and would have been fine when fishdog originally posted it 2 years ago, however any of the newer HE boilers require a permanent feed and to use the internal link to power external controls.
Your heating system will operate if wired as per diagram, but if there is a problem under warranty and the boiler manufacturer sends out an engineer, the engineer will null and void the warranty unless it is wired as per their own wiring diagram.

2011

Look Gary & Eoghan "without going all boiler nerdy" I take your point and agree that you should never go against the manufacturers recommendations, I am not suggesting otherwise!

The OP was looking for an explanation of how external controls (such as a time clock, zone valves and stats) work/can be wired. The wiring diagram shown is suitable for many boilers/houses out there, but not all. However it can be used as a basis for design that may need to be tailored to suit the requirements of a particular boiler or heating system.

As Gary71 correctly said some boilers use a volt free NO contact to fire the boiler. In that case arrangement as shown in the circuit diagram could still be used but it would be energising a NO relay. That way an external supply does not get connected to these terminals.

It should go without saying that this type of work should only be carried out by a suitably qualified person. Such a people know that you don't just go connecting mains voltage to expensive boilers without doing a bit of research first, such as reading the manual!!!

The same applies to wiring in general; good general advice can be given, but there are very few situations that a diagram can be supplied that will cover all situations.

M cebee

ya.
the old drawing is a good basic drawing and the permanent feed+switched live is still used for some new oil boilers .

it can be adapted to a 'call loop' as 2011 said with a simple relay

2011

the permanent feed+switched live is still used for some new oil boilers .

+ 1
I am looking at a brand new Vokera boiler right now that requires this.

I think that people in general want wiring that is more "intelligent". This not only makes it more effective, but it cuts down on energy costs.

Bruthal

gary71 wrote: »

Without going all boiler nerdy:), i wouldn't advise that design with a gas boiler with a link for external controls, the reason is it's good working practice(and i don't see it often) to bring back to the link what ever originated on the other side of it after it's gone via external controls, the boiler could be low voltage/no voltage switching or more importantly some boilers cut the power going out on the first part of the link if a safety device kicks in, so if there is a moody power coming back to the boiler then the safety devices have been bypassed and the boiler can still fire which can lead to death or injury, which has happened in the past, Gary.

Yes i`d agree with everything there

youtheman

Folks, I have a related question.

My boiler currently has external controls via a combined thermostat/timer. When the external contact opens the boiler stops firing, and the internal controls ensure that the pump runs on.

I've fitted two actuated valves (with the actuators off until I commission the controls). I've looked up the boiler wiring instructions, and I've even gained clarification from the boiler manufactureer as to how to wire it. But I still have a query about the ability of the pump to run on when the timer or thermostat opens.

The boiler stops firing if both actuated valves are closed (via the valve position switch). If a thermostat reached the set point it opens, thus closing the actuated valve which in turn will stop the boiler from firing. But if the actuated valve is closed then the pump will dead head (asuming it is trying to run on). Do you know if this is normal ?.

Bruthal

youtheman wrote: »

Folks, I have a related question.

My boiler currently has external controls via a combined thermostat/timer. When the external contact opens the boiler stops firing, and the internal controls ensure that the pump runs on.

I've fitted two actuated valves (with the actuators off until I commission the controls). I've looked up the boiler wiring instructions, and I've even gained clarification from the boiler manufactureer as to how to wire it. But I still have a query about the ability of the pump to run on when the timer or thermostat opens.

The boiler stops firing if both actuated valves are closed (via the valve position switch). If a thermostat reached the set point it opens, thus closing the actuated valve which in turn will stop the boiler from firing. But if the actuated valve is closed then the pump will dead head (asuming it is trying to run on). Do you know if this is normal ?.

Usually a bypass would be fitted at the hot water cylinder with a gate valve in it. It is just a pipe between the flow and return into the cylinder heating coil with the gate valve open just a half or 1 turn, the bypass is before the cylinder actuator valve so that if rad actuators and hot water cylinders are closed the pump can still run a few minutes and the bypass allows some flow. The pump keeps running to dissipate heat from the boiler after the flame goes out.

The hot water cylinder coil will have a gate valve for controlling the flow into the actual coil also to facilitate balancing the system.

If the hot water cylinder does`t have an actuator or thermostatic valve then no bypass is needed.

youtheman

Thanks Robbie. I just spoke to the boiler manufactureer again and he said it was o.k. to 'dead head' the system as there was an automatic bypass fitted (which backs up your comment)

I was aware that there was a bypass fitted. It is internal to the boiler (just a 'short circuit' between the outlet and inlet). I can see there is an advantage of running the pump on after the thermostat has opened as there is still a lot of residual heat in the system, and you might as well us it (by flowing through the radiators, as I can do with the existing system).

So now with the actuated valves the system will rely on the bypass. If that's o.k. with the boiler manufacturer then it's o.k. by me. But I would have throught that it reduces the efficiency of the system as you cannot use the residual heat in the system (after the boler has stopped firing).

Bruthal

youtheman wrote: »

Thanks Robbie. I just spoke to the boiler manufactureer again and he said it was o.k. to 'dead head' the system as there was an automatic bypass fitted (which backs up your comment)

I was aware that there was a bypass fitted. It is internal to the boiler (just a 'short circuit' between the outlet and inlet). I can see there is an advantage of running the pump on after the thermostat has opened as there is still a lot of residual heat in the system, and you might as well us it (by flowing through the radiators, as I can do with the existing system).

So now with the actuated valves the system will rely on the bypass. If that's o.k. with the boiler manufacturer then it's o.k. by me. But I would have throught that it reduces the efficiency of the system as you cannot use the residual heat in the system (after the boler has stopped firing).

Well the the residual heat would be very little compared to the heat the system generates anyway, so not a lot is lost overall, if the bypass flow was to a bypass fitted at hot water cylinder then the residual heat would be lost in the pipes in walls or under floors anyway, so not a major difference. Its really just to stop water boiling or overheating in the heat exchange of the boiler.

Psullie13

can anyone help me? I have a combi gas boiler, 2 channel programmer,2 wireless stats and two motorised valves, and wish to wire it. Does anyone have any advise or a drawing preferably to help me???????