Zone control or other option???

[TheOriginalTableLeg]

Can anybody please tell me what would be the best thing to do to try and help with the following problem.

During the recent cold spells we found that we really needed the heating on all night.

We have 3 bedrooms and these are on one end of our property with the kitchen, lounge and dining room at the other end. All of our bedrooms have TRV's but none of the other rad's have them.

Having the heating on through the night also meant heating the kitchen, lounge and dining room which only really needed slight warmth if anything.

Is it worth putting TRV's onto the lounge and dining room rad's (and leave the kitchen rad without one to allow pump flow when other trvs are closed) or would it be worth splitting the bedrooms from the rest of the house using a 2 zone circuit with a room stat in the living room (which adjoins thekitchen and dining room) and a second in the hallway leading to the bedrooms???

To add:
I currently have 1 pump and a mid way 3 port valve for CH and DHW.

Any advice greatfully received.

 

[ianniann]

Sounds like you have a pretty good situation for two zones. Having TRVs on the radiators wouldn't really solve your problem because you would still be heating the other end of the house to keep the bedrooms warm. You could turn the TRVs down every night but that isn't really the best solution. Use zones and heat each end at different times to suit your needs.

 

[TheOriginalTableLeg]

Thanks for the reply

Thats exactly what I thought about the TRV's. Pain to adjust them each day and night.

Can you offer any advice on the S plan plus?

From what I have read so far, I can retain my pump, but I would need 3 new 2 port valves, is that right?

Can I retain the programmer?

Do I need a bypass valve?

Thanks again.

 

[D_Hailsham]

During the recent cold spells we found that we really needed the heating on all night.

What insulation do you have - cavity wall, loft, double glazing?

If none, you can get very good deals at the moment. Check out Energy Savings Trust Grant Search

From your description you appear to live in a bungalow, am I correct?

Zoning the living area and bedrooms separately would be the best solution, but you need to know how system is piped as it may need modification so you can control one zone independently from the other.

You would need a programmable thermostat for each CH zone and a timer for the HW zone. All rads should have TRVs except the rad controlled by the thermostat.

The 3-port valve would have to be replaced by three 2-port zone valves.

If the boiler does not have one, you will have to fit an automatic bypass valve.

 

[TheOriginalTableLeg]

Thanks very much for the reply

What insulation do you have - cavity wall, loft, double glazing?

Cavity wall insulation, loft is about 200mm and we have UPVC double glazing all round.
I should add, we had an extension a few years ago which is now where the bedroom are. This part of the bungalow is noticeably cooler than the rest of the bungalow. But it is joined to our garage which with the draughty garage door has 2 of the 3 external walls are single brick.

From your description you appear to live in a bungalow, am I correct?

Absolutely spot on

Zoning the living area and bedrooms separately would be the best solution, but you need to know how system is piped as it may need modification so you can control one zone independently from the other.

You would need a programmable thermostat for each CH zone and a timer for the HW zone. All rads should have TRVs except the rad controlled by the thermostat.

The 3-port valve would have to be replaced by three 2-port zone valves.

I currently have a Honeywell ST6400C programmer.
1x Honeywell digital room stat DT200.

HW is gravity.

Mid positon valve pumps to HW cylinder coil, rads or both.

Whether the boiler has a bypass I do not know. It is an HRM Wallstar (oil boiler).

Does this extra info help?

 

[D_Hailsham]

I should add, we had an extension a few years ago which is now where the bedroom are. This part of the bungalow is noticeably cooler than the rest of the bungalow. But it is joined to our garage which with the draughty garage door has 2 of the 3 external walls are single brick.

No wonder you feel cold at night! Have you investigated ways of insulating the single brick walls to prevent the massive heat-loss through them?

I currently have a Honeywell ST6400C programmer.
1x Honeywell digital room stat DT200.

You could retain that to control one CH zone and the HW and buy a programmable stat for the second CH zone.

HW is gravity.

Mid positon valve pumps to HW cylinder coil, rads or both.

The HW may come out of the tap due to gravity, but it is heated by pumped circulation through the coil in the cylinder. Plumbers and heating engineers do not refer to this as gravity HW which, to them means that the water is heated by natural circulation (hot water rises, cold water falls), not pumped circulation. Confusing, I know, but that's how it is.

Whether the boiler has a bypass I do not know. It is an HRM Wallstar (oil boiler).

Do you know which model Wallstar?

 

[mikely]

An easier possible solution you could try first is to simply replace your thermostat with a programmable version. Set this to a night set-back temperature and this will bring the heating on at a low level on colder nights. This will obviously heat the whole house but you should find that the heating does not need to be on too much to maintain a set-back temperature at around, say 12-15C. Nothing would be lost because, if you proceed with zoning the system, you will need the new thermostat anyway.

One other thought. Is your bedroom extension furthest from the boiler and do the radiators get adequately warm? Just wondering if you have a balancing problem. If your new extension was built correctly to recent building reg’s, it is surprising that it is the coldest part of the house.

 

[TheOriginalTableLeg]

Many thanks once again for the reply .

No wonder you feel cold at night! Have you investigated ways of insulating the single brick walls to prevent the massive heat-loss through them?

I have yes. I have already completely insulated the roof. I could replace the garage door but that would cost near on £1000! and with regards to the walls, I got mixed advice.

Do you know which model Wallstar?

Wallstar 15/20

 

[TheOriginalTableLeg]

Many thanks for the reply.

One other thought. Is your bedroom extension furthest from the boiler and do the radiators get adequately warm? Just wondering if you have a balancing problem. If your new extension was built correctly to recent building reg’s, it is surprising that it is the coldest part of the house.

The bedrooms in the extension are furthest away from the boiler but the rads heat up quickly and get as hot as any other. There is no problem with the temperature of the rads in the extension.

The extension was built to the regs including cavity wall insulation and the correct amount at the time about 200mm loft insulation.

 

[TheOriginalTableLeg]

Ok, ive just been reading about the programmable room stats. Am I right in thinking that I could retain my existing programmer and room stat for the bedrooms and use a new programmable stat in the lounge.

With the fitment of 3x 2 port valves, and 2x of them wired separately to each of the room stats?

Is that how it works?

I take it the existing programmer cannot be used for the new 2 port valves?

 

[D_Hailsham]

Ok, ive just been reading about the programmable room stats. Am I right in thinking that I could retain my existing programmer and room stat for the bedrooms and use a new programmable stat in the lounge.

Yes

With the fitment of 3x 2 port valves, and 2x of them wired separately to each of the room stats?

Yes, the third valve would be controlled by the HW cylinder thermostat

I take it the existing programmer cannot be used for the new 2 port valves?

It could be, but you would then need a thermostat for the second heating zone and a programmer for the HW. If you retain the existing programmer for one CH zone and the HW, there would be minimal changes to the wiring of the existing programmer, CH stat and HW stat to convert over to separate zone valves for the HW and one heating zone. Also the programmer is probably labelled for HW and CH!!

The CM927, the wireless version of the CM907 would make installation even easier as there would be no wires to run from the thermostat to the boiler, only from the receiver, which can be located near the other equipment.

Here is a wiring diagram for a S plan plus with the CM900. The wiring is slightly different for the wireless version. Click the image to enlarge then right click to save.

View media item 30349
Have you checked that the pipe layout will allow you to have two completely separate heating zones? See the following sketch:

Untitled

• D_Hailsham
• 20 Jan 2011
• 2

 

[TheOriginalTableLeg]

What a fantastic reply .

I am extremely grateful for the time you have taken to respond in such an in depth way, including the diagrams.

I think that pretty much tells me all I need to know.

I just need to find time to go up into the loft and check out the routing of the pipework.

Many many thanks again.

 

[TheOriginalTableLeg]

D_Hailsham,

Can you please cast your eye over the following 2x images and tell me if I understand you correctly?

Existing layout
View media item 30369Power to junction box provides power to and from programmer, cylinder stat, room stat, pump and 3 port diverter valve.


New layout
View media item 30370Retain programmer linked to current room stat., this would be wired to the HW 2 port valve and one of the other 2 port valves.

New programmable Room stat would be wired to the remaining 2 port valve (via junction box).

 

[D_Hailsham]

Existing layout

[pic]

Power to junction box provides power to and from programmer, cylinder stat, room stat, pump and 3 port diverter valve.

The junction box also provided power to the boiler, via the cyclinder thermostat or the mid position valve. (Se the wiring diagram)

New layout

[pic]

Retain programmer linked to current room stat., this would be wired to the HW 2 port valve and one of the other 2 port valves.

New programmable Room stat would be wired to the remaining 2 port valve (via junction box).

Correct, but each 2-port valve is wired (via the junction box) to the boiler.

When a thermostat opens, a valve a switch in the valve closes and makes a circuit between the grey and orange wires. This supplies voltage to the boiler which then lights.

Which make and model boiler do you have? This can affect how the valve switches are wired - may not be as in the wiring diagram.

 

[TheOriginalTableLeg]

Which make and model boiler do you have? This can affect how the valve switches are wired - may not be as in the wiring diagram.

Thanks once again

Boiler is an HRM Wallstar 15/20.

I tried to find out if it had a relief valve to protect the pump. No idea though.
Is it needed? As it is my boiler seems to switch straight off when the stat temp is reached.