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 ..

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?

Wireless motorized valve controllers ?

Jan 23, 2006 23 Replies

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Geronimo W. Christ Esq 20 years ago

No, it has never tripped on me.

The setting is at about 9 o'clock on the dial which is pretty low. Even then the boiler cycling is quite bad (off for about 40 seconds, on for about two minutes continuously). When I set the thermostat higher than this the cycling is even worse. It is the cycling that has led me to consider taking action to get the system properly set up.

Thanks. I don't feel sufficiently competent to start messing around at this, but I appreciate being informed about how it should be expected to work :)

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Set Square 20 years ago

Cycling occurs when the rate at which your boiler is producing heat is greater than the rate at which the radiators and HW cylinder coil can dissipate it. It should cycle *less* if you turn up the boiler stat because with the radiators being hotter, they can dissipate more heat. Have you tried increasing the pump speed?

If the boiler *still* cycles excessively when the house is hot enough in the coldest weather, it sounds as if it's too big for the job. You can probably reduce the boiler output a bit by reducing the gas pressure. This will be explained in the installation manual.

Actually, re-reading what you wrote above - indicating that the boiler is firing for 120 seconds in every 160 (i.e. 75% of the time) I wouldn't worry about it if it only does it in steady state conditions. [I would expect the boiler to run continuously for much longer than that when first starting up from cold - does it?]

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Geronimo W. Christ Esq 20 years ago

I haven't tried messing with the pump speed (was concerned that this might cause overflow into the header tank?) but I may experiment based on your advice.

I will have a go at turning the thermostat up and measure the rate at which cycling occurs. To be honest with you, I am not long moved into the house and I'm still trying to find my feet regarding which radiators to leave on or off while the system is running, and how long to run the timer for. I'm in Northern Ireland and we pay stupendous amounts for gas over here, so it's about trying to get a balance between heating the place sufficiently and not getting an insane gas bill ;)

The boiler burns continuously for about 45 minutes from cold before it enters the state where the cycling occurs. After this time I've got a full cylinder of nicely hot water.

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Set Square 20 years ago

That sounds perfectly normal to me - and certainly nothing to worry about.

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