Central Heating controls

n0brain3r

Hi all,

I've a Siemens RWB 29 timer on my boiler. It has separate programs for both heating and hot water. At the moment I've everything wired to the CH terminal so boiler, circulating pump and motorized zone valves all operate on the CH program.

I've switched lives at the timer the boiler, circulating pump and motorized valves.

I'd like to have the following setup CH powers all 3 circuits so providing heating and hot water but that the HW powers only 2 the boiler and circulating pump.

I've been able to get it to function as above but the motorized valves are always powered and are only turned off when the HW program runs and I'd like to avoid this if possible.

The wiring diagrams and manual for the timer are here http://www.leeds.gov.uk/docs/Boiler%20and%20Heating%20information%20-%20siemens%20rwb%2029.pdf

Can anyone suggest a better way to wire it to achieve what I'm after?

Sir Arthur Daley

n0brain3r wrote: »

I've been able to get it to function as above but the motorized valves are always powered and are only turned off when the HW program runs and I'd like to avoid this if possible.

This is confusing, can you put up a drawing of your installation?

n0brain3r

I'll try get a pic up tomorrow but here the txt of what I did.

I powered the thermostats/zone valves from the HW off terminal and the boiler and circulating pump from the CH on terminal. I then looped the HW on terminal to th CH on terminal. When the cH program runs all 3 are powered but when the HW program runs only the boiler and pump are powered but when CH and HW are off the thermostat/ zone valves s are powered which I wanted to avoid. There's a switch/terminal diagram in the pdf linked above if it helps too

n0brain3r

Ok heres the graphic I hope it makes sense!

frankmul

I think that we need to know how you have the stats and the valves wired. The switch on the valve should bring on your boiler.

2011

frankmul wrote: »

The switch on the valve should bring on your boiler.

+1
This is a good way of bringing the boiler on.

2011

n0brain3r wrote: »

Ok heres the graphic I hope it makes sense!

By connecting the stat & zone valves to terminal #1 these devices will only be powered when the HW channel is off. This is not what you want.

n0brain3r

frankmul wrote: »

I think that we need to know how you have the stats and the valves wired. The switch on the valve should bring on your boiler.

For the stats and valves I only have a single wire back at the boiler. I'm guessing this splits and runs via the 2 stats and on to the valves. I've 5 wires at the boiler neutral, live and a switched live to the boiler, pump and stats.

2011 wrote: »

By connecting the stat & zone valves to terminal #1 these devices will only be powered when the HW channel is off. This is not what you want.

I know but it works crudely when the CH program runs the boiler, pump and stats are powered (HW is off) so I have CH and HW and when the HW program runs only the boiler and pump run as the stats are switched off so I have just HW. I just don't like having the stats powered all the time and wasn't sure how electrically safe this was either.

Sir Arthur Daley

n0brain3r wrote: »

I just don't like having the stats powered all the time and wasn't sure how electrically safe this was either.

As in room stat and hw stat on cylinder?

2011

How many stats?
What does each stat serve?
How many zone valves?
What does each zone valve serve?

Answer the above and a diagram will be posted by myself or someone else.

n0brain3r

What does each stat serve?
2 stats one for upstairs and one downstairs

How many zone valves?
3, 2 on the room stats and one TRV type on the cylinder

What does each zone valve serve?
1 upstairs
1 downstairs
1 hot water cylinder(TRV type)

thanks!

Sir Arthur Daley

You are not taking advantage of your seperate heating zones with your current clock, why not get a 3 channel one?

n0brain3r

Sir Arthur Daley wrote: »

You are not taking advantage of your seperate heating zones with your current clock, why not get a 3 channel one?

I only have a single live for both zone valves at the clock and wanted to do the best with what I have thanks for the suggestions though!

Sir Arthur Daley

Have the motorised valves got an auxillary contact?

n0brain3r

Sir Arthur Daley wrote: »

Have the motorised valves got an auxillary contact?

I don't know they're Danfoss ill try attach a pic too

Sir Arthur Daley

How many wires are in the flex?

n0brain3r

There's 4 in the flex label on the side says type HPA2 p/n 5927

2011

This will do it for you.
However it requires a 3 channel time clock as Sir Arthur Daley suggested.

Sir Arthur Daley

He could use the single CH output on his clock to supply the two stats.

2011

Sir Arthur Daley wrote: »

He could use the single CH output on his clock to supply the two stats.

True.
Personally I would prefer the 3 channel.

Sir Arthur Daley

2011 wrote: »

True.
Personally I would prefer the 3 channel.

I would too as you are utilising your zones.

He could use the HW to bring on one CH zone and HW and use the CH from clock to bring on the other CH zone. Just turn down the stat then whenever you dont want heating on the zone the HW is coming from.

Bruthal

2011 wrote: »

This will do it for you.
However it requires a 3 channel time clock as Sir Arthur Daley suggested.

In my opinion the valve contacts should be connected to the boiler control loop, where there is one, rather than be fed directly from the circuit live. In most cases its probably simply taking a link from the boiler permenant live terminal anyway. But it's better practice to use the terminals in the boiler control board.

Obviously if the boiler has switched live and permanent live terminals, then the diagram is perfect. Any I seen have a set of control loop terminals.

Sir Arthur Daley

Do you mean take the live on the boiler side of the isolater for the auxiliary contacts?

Bruthal

Sir Arthur Daley wrote: »

Do you mean take the live on the boiler side of the isolater for the auxiliary contacts?

Gas boilers usually have L N E terminals. They are supplied by the fused spur.

There is a link to be removed at the terminal block. And the 3 zone motor valve switches all wired in parallel, are connected into where the link was.

It might be an oil boiler in this case.

Sir Arthur Daley

The drawing is for an oil boiler set up i imagine, im with you on the gas boiler that volt free link.

Sir Arthur Daley

I get the impression from op that his boiler is oil.

Bruthal

If I'm reading correctly what the op is trying to do, then the HW channel can bring on the pump and boiler.

The CH channel can bring on a DP relay.

Connect zone valves to one pole. And other pole can switch in parallel with HW channel.

So HW switches only pump and boiler. CH brings all on. I think that's what OP was asking for.

But if there are 3 motorised valves, the one for HW has to come on with HW channel once it's stat is closed.

Anyway, relays can be used to keep different items isolated from each other with reference to exactly what's needed.

Bruthal

Sir Arthur Daley wrote: »

I get the impression from op that his boiler is oil.

Yea I have that in last post myself.

Sir Arthur Daley

Bruthal wrote: »

If I'm reading correctly what the op is trying to do, then the HW channel can bring on the pump and boiler.

The CH channel can bring on a DP relay.

Is there need of the relay, just let the ch output of clock power the stats, cant he have the hw time period come on the same as the ch?

Bruthal

Sir Arthur Daley wrote: »

Is there need of the relay, just let the ch output of clock power the stats, cant he have the hw time period come on the same as the ch?

He could. I actually drew it out just like that. But a relay is how I'd do it. Keeps it simpler to operate.

But I'm not completely clear on the setup. Are the valves simply being used as valves?

Are their contacts being used?

A pipe stat giving pump over run might be good as well. Might be OK without it on oil boiler though.

Sir Arthur Daley

Bruthal wrote: »

Are their contacts being used?

I dont think he knows about that, i asked that earlier.

Are the valves simply being used as valves

I believe so, this is his only way to achieve zoning.

A pipe stat giving pump over run might be good as well. Might be OK without it on oil boiler though.

Good idea, oil boilers can trip out the high limit especially if the thermostat is turned up high.

Bruthal

Sir Arthur Daley wrote: »

Good idea, oil boilers can trip out the high limit especially if the thermostat is turned up high.

Yea that's the main problem with no over-run alright.

Sir Arthur Daley

Bruthal wrote: »

If I'm reading correctly what the op is trying to do, then the HW channel can bring on the pump and boiler.

The CH channel can bring on a DP relay.

Connect zone valves to one pole. And other pole can switch in parallel with HW channel.

So HW switches only pump and boiler. CH brings all on. I think that's what OP was asking for.

Just getting back to this configuration, that is a nice simple way of giving hw only or hw and ch. It may be possible to set the clock up to give hw if ch is selected like in the conventional analogue grasslan or flash ones.

Bruthal

Sir Arthur Daley wrote: »

Just getting back to this configuration, that is a nice simple way of giving hw only or hw and ch. It may be possible to set the clock up to give hw if ch is selected like in the conventional analogue grasslan or flash ones.

With the relay used, it will give either HW alone, or CH and HW.

All assuming we are seeing correctly what was being described:)

Sir Arthur Daley

Bruthal wrote: »

With the relay used, it will give either HW alone, or CH and HW.

All assuming we are seeing correctly what was being described:)

Yea on the ball, i guess a 3 channel clock is the way to go to get the benefits of the zones. If he wants to keep the 2 channel my suggestion in post 21 would be a way of gaining seperate heating zones. I know if he switches on the other ch the hw wont come on but one could put in relays and configure to achieve seperate ch and have hw come on with each and in the summer just turn down the room stats.

Bruthal

I don't think the op has access to separate zones for upstairs and downstairs. Think he said he thinks a single switch wire leaves timer and splits to 2 stats and valves.

The 3 items he can switch are pump, boiler, and valves for radiators from what I can see. So a 3 channel time clock won't work properly either if that's the case.

I could be seeing it wrong though. Don't seem to be seeing too clearly lately.

Sir Arthur Daley

Bruthal wrote: »

I don't think the op has access to separate zones for upstairs and downstairs. Think he said he thinks a single switch wire leaves timer and splits to 2 stats and valves.

In post 11 he says he has 3 valves, 2 for ch and one for hw.

Bruthal

Sir Arthur Daley wrote: »

In post 11 he says he has 3 valves, 2 for ch and one for hw.

He has the valves, but has he got the switch wires?

Sir Arthur Daley

Bruthal wrote: »

He has the valves, but has he got the switch wires?

Good point, he needs to tell us what he has at the clock.

If its plumbed for 3 zones surely it was wired sufficiently to accommodate it.

n0brain3r

2011 wrote: »

This will do it for you.
However it requires a 3 channel time clock as Sir Arthur Daley suggested.

That would be my ideal setup but I don't think I have enough wires at the timer only 1 for boiler, 1 for the circulating pump and 1 that powers the circuit with the room stats and zone valves on it.

Bruthal wrote: »

If I'm reading correctly what the op is trying to do, then the HW channel can bring on the pump and boiler.

The CH channel can bring on a DP relay.

Connect zone valves to one pole. And other pole can switch in parallel with HW channel.

So HW switches only pump and boiler. CH brings all on. I think that's what OP was asking for.

But if there are 3 motorised valves, the one for HW has to come on with HW channel once it's stat is closed.

Anyway, relays can be used to keep different items isolated from each other with reference to exactly what's needed.

Thats it exactly 2 mororised valves one for upstairs and one for downstair the cylinder/HW is a TRV like on a radiator.

Bruthal wrote: »

He could. I actually drew it out just like that. But a relay is how I'd do it. Keeps it simpler to operate.

But I'm not completely clear on the setup. Are the valves simply being used as valves?

Are their contacts being used?

A pipe stat giving pump over run might be good as well. Might be OK without it on oil boiler though.

I think just valves there's 4 wires in each valve but only 2 used on each.

Bruthal wrote: »

I don't think the op has access to separate zones for upstairs and downstairs. Think he said he thinks a single switch wire leaves timer and splits to 2 stats and valves.

The 3 items he can switch are pump, boiler, and valves for radiators from what I can see. So a 3 channel time clock won't work properly either if that's the case.

I could be seeing it wrong though. Don't seem to be seeing too clearly lately.

That's it exactly

Bruthal wrote: »

He has the valves, but has he got the switch wires?

I don't think so

Sir Arthur Daley wrote: »

Good point, he needs to tell us what he has at the clock.

5 wires neutral, live, live to boiler, live to circulating pump and a single live to the 2 valves and stats I'm guessing it must split somewhere to serve each.

Its a gas boiler too btw

thanks for all the replies!

Sir Arthur Daley

Is there a big joint box in hotpress where mv are?

n0brain3r

Yes I think this is where the live from the clock is distributed to the stats which feed back to the mv

Sir Arthur Daley

n0brain3r wrote: »

Yes I think this is where the live from the clock is distributed to the stats which feed back to the mv

Can you open it and put up pics along with clock wires and boiler, interested in seeing it.

n0brain3r

Sure will grab some pics in the morning thanks for bearing with me!

Bruthal

Why do you think one of the switched wires is to the pump? Is it not a system boiler with pump, pressure gauge, expansion vessel etc all built into it?
Is the timer beside the boiler?

Are there 3 motorised valves in the hot press?

My own house is not done properly either. Only one valve in hot press to do all radiators. And it does not turn them off. Probably not closing propely. I keep meaning to put in a hand valve to test, then replace motorised valve.

n0brain3r

Bruthal wrote: »

Why do you think one of the switched wires is to the pump? Is it not a system boiler with pump, pressure gauge, expansion vessel etc all built into it?
Is the timer beside the boiler?

Are there 3 motorised valves in the hot press?

My own house is not done properly either. Only one valve in hot press to do all radiators. And it does not turn them off. Probably not closing propely. I keep meaning to put in a hand valve to test, then replace motorised valve.

I was wrong on having the pump I drew it out like that when trying to figure out how to wire the system for more control but it's a single wire to the boiler and pump.

Timer is beneath the boiler.

I've attached PICs of the wiring an valve layout I've only got motorized valves for up and downstairs the cylinder is a TRV type valve based on the temp of the cylinder.

frankmul

How does a boiler interlock work with that cylinder trv?

K.Flyer

frankmul wrote: »

How does a boiler interlock work with that cylinder trv?

It doesn't, and there is no sign of any automatic by-pass either.

Rip it out and start again:eek: wire it as a S-plan with a 3 channel programmer (as mentioned), whatever it costs it will cheaper than the repair costs that will be needed down the road and you would then have a boiler with interlocks helping reduce fuel costs and it would just be right.

Wiring for gas boilers is regimented, it starts with the boilers specific requirements all day every day, the requirements can differ from boiler to boiler but is usually a variation of a S plan, Y plan or W plan depending on the plumbing configuration, always follow the boilers MI and not the wiring instructions that come with the external control packs.

With bad heating system design the wiring is very important as bad wiring can exacerbate any problems with the installation. To wire other than the specific boiler requirements commonly leads to blown pcb boards, boiler safety devices bypassed(at times), power coming on to the boiler after local electrical isolation.

Systems like this should really be a thing of the past as they damage the boilers longevity, lead to higher fuel costs and the sparks can get reported for wiring a gas boiler not to current standards.

Also with a added external pump overrun and domestic gas boilers, it's not needed if it was the boiler would be dealing with it or the MI would be specifying it , if you find yourselves looking at this as a option then your usually dealing with symptoms of a problem and not the problem.

n0brain3r

K.Flyer wrote: »

It doesn't, and there is no sign of any automatic by-pass either.

Should I be worried an interlock would stop the boiler firing if no zone called for heat and the timer switched the boiler on right? Whats an automatic bypass? The manual says it has one internally will this do? It's an Ideal Mini S24 manual is here http://idealboilers.com/installer/wp-content/uploads/sites/2/2013/08/mini_is32.pdf

gary71 wrote: »

Rip it out and start again:eek: wire it as a S-plan with a 3 channel programmer (as mentioned), whatever it costs it will cheaper than the repair costs that will be needed down the road and you would then have a boiler with interlocks helping reduce fuel costs and it would just be right.

Wiring for gas boilers is regimented, it starts with the boilers specific requirements all day every day, the requirements can differ from boiler to boiler but is usually a variation of a S plan, Y plan or W plan depending on the plumbing configuration, always follow the boilers MI and not the wiring instructions that come with the external control packs.

Do you mean replace just the clock or everything zone valves and rewiring etc.?

I think the wiring that applys to my setup is on pg. 24 of the pdf linked above all I did was replace a failed analogue single channel clock so I don't think it was ever wired properly?

gary71 wrote: »

With bad heating system design the wiring is very important as bad wiring can exacerbate any problems with the installation. To wire other than the specific boiler requirements commonly leads to blown pcb boards, boiler safety devices bypassed(at times), power coming on to the boiler after local electrical isolation.

Systems like this should really be a thing of the past as they damage the boilers longevity, lead to higher fuel costs and the sparks can get reported for wiring a gas boiler not to current standards.

Also with a added external pump overrun and domestic gas boilers, it's not needed if it was the boiler would be dealing with it or the MI would be specifying it , if you find yourselves looking at this as a option then your usually dealing with symptoms of a problem and not the problem.

It was installed in 2008 would it of been the norm then? I just checked with the neighbour and his is identically wired. What would added external pump do (I may have confused things I'm not looking to add one) and whats an MI ?

n0brain3r

n0brain3r wrote: »

Should I be worried an interlock would stop the boiler firing if no zone called for heat and the timer switched the boiler on right? Whats an automatic bypass? The manual says it has one internally will this do? It's an Ideal Mini S24 manual is here http://idealboilers.com/installer/wp-content/uploads/sites/2/2013/08/mini_is32.pdf

Never use a inbuilt boiler bypass as a system bypass(even if the MI asks for it) as they block very easily with dirty systems, good working practise and system longevity requires a auto bypass to be fitted external to the boiler.

n0brain3r wrote: »

Do you mean replace just the clock or everything zone valves and rewiring etc.?

I think the wiring that applys to my setup is on pg. 24 of the pdf linked above all I did was replace a failed analogue single channel clock so I don't think it was ever wired properly?

I mean take out all the wires, buy a 3 channel programmer and correctly connect all the components you have as a S plan with the H/W channel firing the boiler direct.

The diagramed shows a mid position valve which is the most common type of installation in the UK your more interested in a S plan.

I'd think about a frost stat as well if one isn't fitted.

n0brain3r wrote: »

It was installed in 2008 would it of been the norm then? I just checked with the neighbour and his is identically wired. What would added external pump do (I may have confused things I'm not looking to add one) and whats an MI ?

Strangely enough "what's MI?" is a question I get most weeks from sparks, it means manufactures instructions:D

It was never the norm, gas boiler wiring is regimented and hasn't really changed in over forty years, you wire this as a S plan utilising the switching of the M/Vs.

Forget about the pump overrun, I was just responding to a suggestion you may want to add it, you don't.