Wireless motorized valve controllers ?

[Geronimo W. Christ Esq]

Hi all,

I recently moved into a house which has a traditional CH and HW system, ie cylinder/header tank/gas boiler, but no controls which allow me independent control of either or both - there is one timeswitch that turns the whole thing on or off. I would like to upgrade this to add a proper control digital programmer that will allow me to program various on/off times for the hot water and heating independently, as I'm finding there are many times when I need one but not the other and it's clearly not efficient to keep a cylinder of water warm all day in the winter (and in the summer, I don't want to have to go around the house and turn down all the TRVs manually when I just need water).

My understanding is that this is a matter of adding two motorized valves, one to open the HW circuit and one to open the CH circuit - then drop in the programmer and bob's your uncle. However, I recognize that this means a control cables will need to be run to each of these valves. Because the cylinder (where the valves will need to go near) is upstairs and the boiler and present timeclock are downstairs, this will mean gouging out of walls, requiring lots of tiling and replastering that I don't want to contemplate at the moment.

What would be really great would be a way to add this wirelessly. This way I could stick the box on the wall, and then have it talk over a radio link to the two motorized valves as required.

Alternatively, the present timeswitch obviously sends a control signal up to switch on the pump which is right beside the cylinder. I guess it just switches mains onto it. I wonder could that arrangement be reversed; I could put the new programmer beside the cylinder, have it control the two valves from there, and then have it use the wire currently used to operate the pump to switch mains downstairs which fires the boiler ?

Advice greatly appreciated ..

[Dave Liquorice]

Or a single three way valve, depending on the plumbing and boiler this may be an easier option. Does the boiler require a bypass if fitted into a fully pumped system?

The only box that doesn't need to be close to the valves/pump is the room stat. Get a programable and wireless one and a single channel wired programmer for the HW. "Reversing" the cable between pump and boiler is not a problem as such but where does the system currently pick up its mains supply?

[Set Square]

Depending to some extent on how many conductors there are in the cable running between the boiler and airing cupboard, and on where the whole lot is powered from, what you want to do is probably possible.

It makes sense to concentrate as much of the electrics as you can in the airing cupboard. The pump is already there. The cylinder stat needs to go there. It's the best [only viable?] place for the motorised valves. The only items which need to be somewhere else are the boiler and the room stat. You already have a cable going to the boiler. You can use a wireless room stat, with the actual switching bit in or near the airing cupboard, and with the wireless sensor/programming unit anywhere you like.

You will, of course, need a source of mains power in the airing cupboard. If the cable from the boiler has enough conductors you may be able to use that - otherwise you'll need to spur an FCU off a nearby power point. Whatever happens, put a proper 10-way junction box in the airing cupboard and wire it all up as per standard S-Plan stuff.

Your main constraint - if there is one - is going to be the existing cable between airing cupboard and boiler - particularly if the boiler needs to control the pump in order to provide pump over-run. You could potentially need five conductors in this cable - Live, Neutral, Earth, Switched Live, and Pump Control. If the boiler doesn't need to control the pump, and doesn't need a permanent live, you can get away with three conductors.

[Ed Sirett]

Anyone know if you can get a plain wireless switch for use in any application not just heating? I expect it would be quite easy to modify a a wireless cylinder stat to do this but I would like to know if there is an off the shelf product?

[Mike Barnes]

The Easy Switch, from TLC, is meant for lighting but I can see other applications. I use one for lighting and it works perfectly.

Well, almost perfectly. It's been 100% reliable but it's on when it should be off and off when it should be on. I get round that problem by using the other switch contact. Things might not be so easy in other applications. The makers might have fixed that problem by now.

[Geronimo W. Christ Esq]

I would have to take a look, but the only wire I know about running up to the cylinder is to control the pump. This is via a fused switch, so I suspect it is just a mains wire coming up from the timeswitch. I am not

100% sure but I do not believe there is any pump control coming from the boiler (a Baxi Solo 3/50 PF); I think the switch just turns the both the boiler and the pump on or off (the pump runs constantly when the system is on). I wouldn't be surprised to crack it open and find both the boiler and the pump appliances wired to the same terminals.

So my idea is, instead of sending the mains signal up to the pump, I can just send the mains down to the boiler. That may involve ensuring that an appropriate mains ring is available. Would it be really stupid or non-compliant to try to get away with hanging it off the same ring that the immersion heater is on ? Having an electrician in to run another ring up to the cylinder would override my objective of avoiding having to rip out walls or tiling to do wiring.

This is probably a stupid question, but is a room stat worth bothering with in the first place, when TRVs are in use and installed ? I see them in new houses around here but most people I know don't have a stat.

Good advice, thank you.

I think I may just about get away with this. The timer seems to be very simple, when it is on it seems to just switch mains into the boiler and pump, when it is off both are stone-dead. I am assuming both the boiler and the pump are not major power users so it should be simple enough to wire them off the main that I have.

Thanks for the advice, greatly appreciated. I think I will see about putting this plan into action.

[Geronimo W. Christ Esq]

I would have to take a look, but the only wire I know about running up to the cylinder is to control the pump. This is via a fused switch, so I suspect it is just a mains wire coming up from the timeswitch. I am not

100% sure but I do not believe there is any pump control coming from the boiler (a Baxi Solo 3/50 PF); I think the switch just turns the both the boiler and the pump on or off (the pump runs constantly when the system is on). I wouldn't be surprised to crack it open and find both the boiler and the pump appliances wired to the same terminals.

So my idea is, instead of sending the mains signal up to the pump, I can just send the mains down to the boiler. That may involve ensuring that an appropriate mains ring is available. Would it be really stupid or non-compliant to try to get away with hanging it off the same ring that the immersion heater is on ? Having an electrician in to run another ring up to the cylinder would override my objective of avoiding having to rip out walls or tiling to do wiring.

This is probably a stupid question, but is a room stat worth bothering with in the first place, when TRVs are in use and installed ? I see them in new houses around here but most people I know don't have a stat.

Good advice, thank you.

I think I may just about get away with this. The timer seems to be very simple, when it is on it seems to just switch mains into the boiler and pump, when it is off both are stone-dead. I am assuming both the boiler and the pump are not major power users so it should be simple enough to wire them off the main that I have.

Thanks for the advice, greatly appreciated. I think I will see about putting this plan into action.

[Geronimo W. Christ Esq]

Easiest is definitely best. I am not sure about the bypass requirements (what does this mean?). It is a Baxi Solo 3 50 PF (gas fired), but the manual does not mention this.

The system is already fully pumped and is not gravity fed. I discussed it about a month or so ago here; the setup is kind of very cheap and non-standard, and not well known to the very helpful experts frequenting the group. Basically there is one timeswitch which turns the entire system on or off, and a pump for the whole caboodle. The cylinder was fitted with a thermostatic valve and a temperature-sensitive strip. No other controls. Needless to say, the assorted chaps on the group were not impressed, for obvious reasons. I'm not too impressed myself either, running the entire system when I just want enough hot water for a shower in the morning, or heating a cylinder full of water when I just need to run a few radiators.

When I moved into the house the termostatic valve on the cylinder was found to be jammed mostly shut and refused to budge. My plumber as a temporary measure removed it (I still have it here on my desk and still can't shift it) just to get me up and running while I gave some thought to a permanent solution up to and including the possibility of a combi. I've decided that a combi is going to be disruptive and expensive to do and potentially a disappointment, so I think I will stick with the existing traditional arrangement, done up "properly" so that it is more cost effective.

I am actually hoping for a single timer with fully independent control over both systems - am I right in saying that the wiring would be a little simpler ? I would like to be wireless everything. If stats are necessary I will probably get a cylinder stat as well. I noticed a programmer which I might get, that provides a temperature readout of both systems - that's a nice touch.

I believe it gets it from downstairs at the timeswitch, and this is the one possible snag in the plan. If I can do it without violating any regulations/laws, I expect I will have to disconnect and isolate the existing mains supply, and run mains down from the new programmer at the cylinder, probably off the ring that the immersion heater is on.

Thanks very much for your help. If I can get the mains power question sorted out then I think I will be armed with a plan to talk over with the plumber.

[Ed Sirett]

OK. Looks like it's a broken install. The Solo 3 DOES operate the pump directly from the boiler. So it look like you'll need a multicore from the airing cupboard to the boiler.

The actual load from the boiler, pump, valves etc is under 1 amp. It is quite common and I beleive compliant to run the heating from the immersion 15A radial circuit.

[Dave Liquorice]

I doubt that the immersion is on a ring but on a 15A fuse or 16A MCB radial. I'm fairly sure there is nothing wrong, regulation wise, with taking a feed for the CH/HW system from that radial via a suitable switched fused connection unit. However if a fault develops in the immersion that requires it to be isolated you also loose power to your CH/HW... Immersions do go faulty.

Recent building regs say that when nothing is calling for heat the boiler must be forced off. This is so that it doesn't cycle just keeping itself hot, thus wasting energy. With a full TRV system you can probably do this with a flow switch but the pump has o keep running through a bypass of some sort, then balancing that flow against a "demand" for heat as a TRV opens may become an issue. Easier to fit a wireless programable room stat in your main living room and take the TRV heads off the rads in that room. The TRVs and room stat will "fight" if you don't.

[Dave Liquorice]

Probably doesn't need one then. A bypass is a means for water to circulate through the boiler core after all the valves (TRV or motorised) have shut. Low capacity aluminium boilers can go into melt down if you just switch 'em off and stop the water flowing at the same time. Larger and/or cast iron boiler don't object.

Wireless adds pennies, quite a few pennies. If the pump, motorised valves, wiring centre, programmer and room stat reciever are all in the air cupboard they can be all hardwired. Wires are very reliable.

I wouldn't run a system without tank and room stats.

[Geronimo W. Christ Esq]

Thanks for the reply, Ed. I need to check exactly what way this is wired, but should I arrange to correct the problem if the pump is not being controlled from the boiler ? Or put another way, if the system is wired up correctly then what would I lose/break if I controlled the pump from the programmer instead ?

The objective here is to avoid running any additional wires between the pump and the boiler. Though, if push comes to shove, I could have a check to see how easy this will be. I don't know if they have just plastered the wire into the wall, or if there will be a duct - if they've put a duct there then it should be nice and easy.

That clears that one up then, thanks.

[Geronimo W. Christ Esq]

OK. This is good advice, I will do as you have said - better to do it right and once, rather than have to go in later and start poking with it again.

[Geronimo W. Christ Esq]

OK, the penny has dropped on how this works after reading the FAQ. The output of the time switch is connected through the thermostat's control. I figure then that the three-port valve would be of the three-position type, such that when two signals are received at once it remains in the mid position, switching to either side position when only one signal is received.

I imagine some slightly less trivial is required for wiring the pump + boiler, since they will switch on if either or both signals are received but never if both are off ? I will leave that part for the plumber to worry about.

[Fred]

If the boiler doesn't have a run-on timer, what's wrong with wiring the pump in parallel with the boiler?

Then just 3 core (ie 2 and earth) would be required which is what I assume he has already?

[Set Square]

When installed properly, a Baxi Solo PF *definitely* needs to control the pump in order to provide pump over-run. Imagine the scenario where the boiler is going flat out, and is suddenly stopped by the room stat. The metal parts of the boiler are *very* hot, and the water inside the boiler will get dangerously hot if it doesn't continue to circulate for a while to carry the residual heat away. If the pump is simply wired in parallel with the boiler, it will stop when the boiler stops - and the boiler will overheat. It may not be a problem with your existing installation because the pump is always on. But when you put a 'proper' control system on it, it will be!

So, as I suggested earlier, you actually need 5 wires beween the boiler and airing cupboard *unless* you cheat! The boiler controls the pump via a thermostat - and keeps it running until the water has cooled sufficiently. But this over-run period is typically a minute or less. What you *could* do is to use a timer - like the ones used with bathroom fans - to keep the pump going for (say) 2 minutes after the boiler demand has been cut. The timer could be installed in the airing cupboard.

The immersion heater is probably on a 15A radial circuit. You can spur an FCU for the heating system - fused at 3A - off that with no problem.

As others have said, for energy conservation you need to turn the boiler right off once both the CH and HW demands are satisfied - and by far the best way of doing this is by using a room stat and a cylinder stat.

One or two people have mentioned by-pass circuits. You may or may not need one. A by-pass provides somewhere for the water the go - principally during the pump over-run period, when the zone valves are closed. If you go for an S-Plan system with 2 x 2-port valves, you will definitely need a by-pass. If you go for a Y-Plan system, with a single 3-port valve, you may not - because there is always at least one port open. Provided you follow the recommendation of having one radiator with two lockshield valves and no TRV - so that it can't be turned off - you're probably ok with a Y-Plan. If you *do* need a by-pass, the easiest way would be to install an automatic by-pass valve between the flow and return, just before the zone valve(s).

[Ed Sirett]

This boiler SHOULD operate the pump (it has an overrun stat). Not to do so is wrong.

[Geronimo W. Christ Esq]

This sounds a bit scary, I better get a plumber to take a look at it. Right now the boiler has been running for about an hour. I turned it off at the timeswitch, and confirmed that the pump definitely goes off. Is this like, a red alert situation or (merely) something that I should try to get sorted at some point in the near future ?

When the timeswitch turns the boiler off, it appears to be completely electrically isolated, so I don't see how it would have a separate mains supply that would allow it to control the pump in that state. Best thing to do is get someone in to have a look at the way this has all been wired.

Yup, the bathroom radiator is setup with two lockshield valves, so I suspect I'll go with Y-plan.

[Geronimo W. Christ Esq]

I have noticed that is expensive, but I will only need a wireless room stat; if I wire everything as you have said (this is the plan) then the tank stat does not need to be wireless.

[Set Square]

If the boiler overheats, it will trip out and have to be re-set manually before it will work again. Presumably you haven't had this? What flow temperature do you currently have? - i.e. what is the boiler thermostat currently set at? If the flow temperature is quite low - maybe to stop the DWH getting too hot - there's a bigger margin of error before residual heat and trippiing becomes a problem. But when you've updated your controls, you try to try to run the boiler at 80 degC - in which case tripping is likely unless you've got some over-run mechanism for the pump.

That's why I said you need *five* wires, as follows:

- Switched live (tells the boiler to fire, as at present)

- Neutral (as at present)

- Earth (as at present)

- Permanent Live [Needed as the source for the pump control signal]

- Pump live [Connected to Live whenever the boiler decides that the pump needs to run]

The boiler is likely also to have a pump neutral and possibly pump earth terminal in addition to the others - but there are plenty of alternative options for neutral and earth floating round in the airing cupboard, so you can leave these unconnected at the boiler end.