What sort of heating system do I have

[con1_uk]

Hi,

I have a small Ideal standard classic LxFF boiler (currently not working correctly see other post on this), upstairs I have a big green tank with a couple of pumps under it which I assume are for HW and CH, I have a thermostat on my wall downstairs which only controls the heating not the water, I don’t seem to have anything to control when the Hw is on but it’s always hot for a shower so assume it keeps a tank warm ready?

what sort of system do I have please and should I have some control over the Hw or leave it as it is?

looking at getting a hive but not sure if I need the ch only model or the CH & HW model.

ta

 

[stem]

That's a bit of a vague description, unfortunately there's not a lot to go on there.

By "big green tank" do you mean something like this? If so it's a 'hot water cylinder'.

Two pumps is rather unusual. Is that what you have? Two of something like this?

Or a twin pump like this?

Or do you mean something like this? Which is a shower pump and has nothing to do with the heating system.

The only thing I would expect to find two of would not be pumps at all but motorised valves. Any of these?

 

[Conbrue]

Hi, yes that's similar to my cylinder

yep, 2 pumps, 1 has HW written on it the other has CH written on it. No shower pump.

I haven't come across and of those motorised valves

Thanks

 

[stem]

A slightly uncommon system, but not unknown. And as you have separate pumps for CH and HW you probably won't have motorised valves as well. As there is a stored hot water supply, then you will need the dual channel Hive.

As Hive controls both the time and temperature of the heating in a single unit, if you connected a single channel Hive to your existing system, the hot water cylinder would only be heated when the central heating was actually running, and by that I mean set to be on and the thermostat calling for heat. So no hot water, unless the radiators were actually on. The second channel is there to allow the hot water to be on independently.

You might be able to keep the existing hot water control, in which case you could use a single channel hive just for the heating, but it could be more difficult to do than replace it, but as you don't have the information about what is presently controlling it it's hard to say Usually there is a programmer that controls the on / off times for the heating and hot water separately.

In either case, here's the thing. For any Hive installation with stored hot water, the heating system & HW must be capable of separate operation. Motorised valves have integral switches to allow either the CH or HW to control the boiler individually. Pumps don't have that facility so I'm wondering from what you say if your system as it stands, will be suitable. This could be quite difficult to ascertain over a forum.

 

[Conbrue]

Thanks Stem, I have never set the hot water its just always been available, I haven't seen anything to control it but it is definitely separate from the central heating as we have hot water in summer. Would the hot water control be in cupboard with the storage tank?

 

[Conbrue]

Hi Stem,

You have replied on my other post about the boiler firing all the time, there are some pictures of my setup on there. I want to get the firing issue sorted before I meddle with a Hive or similar if it is a problem with the boiler etc.

https://www.diynot.com/diy/threads/ideal-standard-lx-boiler-keeps-firing.531540/

 

[ianmcd]

That is not a HW Cylinder it is a Thermal store hence why you have 2 pumps

 

[con1_uk]

Ahh right, so how do I control it? Is it on all the time? I only have a room stat and that’s just for the CH, there is a dial on the actual boiler that controls the water temp but no timer for the water as I know.

will a Hive work in my situation?

 

[ericmark]

Hive duel channel is 230 volt only and on/off only. Nest is what is called volt free so although the heat link it supplied with 230 volt it can switch any voltage and also you can use the N/O and N/C as supply in and com as supply out. Plus it has option for OpenTherm connection to ebus.

However start by explaining what is wrong with old, it may be programmable TRV heads is what you need rather than wall thermostat, also they are far easier to fit. I use bluetooth version of these for upstairs think paid £15 each, and down stairs use these note the energenie needs a hub as well or their own thermostat, they should work with Nest but I have problems getting them to work with Nest.

There is also the Terrier itemp i30 another stand alone head. There are many more, likely Honeywell EvoHome is the best know and been out a long time, also Tado but I don't know how well they work I can talk about eQ-3, Energenie and Nest as I have them in this house.

I stand to be corrected but I think your system is designed so a on/off boiler can heat tank, then the tank heats house so no hysteresis, it is one of the better systems.

 

[ianmcd]

No google how a thermal store works, one pump moves the system water through the sore , the other pump moves the primary water to the rads, the HW is run through a high conduction coil inside the store, your Ideal classic boiler thermostat should be set at max and let the store control everything

 

[con1_uk]

Will nest work on central heating only?

 

[ianmcd]

Will nest work on central heating only?

yes you will have to wire it as a single channel, it will control the CH pump and not the boiler, not a big deal to do

 

[con1_uk]

Brill thanks, I whipped the room thermostat off the wall earlier to see the wires, it has 2, is this ok for Hive/Nest?

 

[stem]

If I'm not mistaken, that looks like a Danfoss TP4/5 thermostat. It has the switching wires there to control the heating, in 'COM' and 'NO' but it is battery powered. Hive and Nest are mains powered, so they also need a 230V supply to power them connecting to their N & L terminals.

This should come from the same fused spur that supplies the entire heating system. The red wire in 'COM' may be a suitable live, provided it's permanent and not controlled by a timeswitch somewhere, but there isn't a neutral. The easiest way is probably just to run a new N & L to the Hive / Nest and then use the existing wires for switching as they are now.

If you are only going to control the central heating then you need a single channel version of Hive.

 

[ianmcd]

if you want the easiest way just replace that thermostat with the nestE it is battery powered and you just connect those two wires to it, but must be NestE not a standard nest