Maximum gas central heating control:7 zones/stats in a standard 3 bed semi-d?

ReadySteadyGo

Hi,

The standard solution, seems to be three zones, each with a programmable stat, (upstairs, downstairs, cylinder) and TRV's for rooms which do not have a stat in them. This appears to be a great solution for the users of the rooms with the programmable stats, but a poor solution for the other rooms.

Specifically
1. Comfort - If the rooms with TRVs are too cold, they can never get the boiler to turn on. The TRVs are not as precise as other stats.
2. Wasted energy - Unless everyone in the house is constantly turning on and off TRV's, the room with the TRV's will be getting heat at times when they don't need it. The room with the wall stat, will likely be deliberately over-heated in order to get the coldest TRV'd room up to a comfortable temperature.

Are there any ways to improve this setup?

I would like maximum control on the heating system in my house. Ideally I would like Zone type functionality in each room. i.e. ability to specify desired time and temperatures for each room, and a 1hr "boost" button for each room.

In my house their would be 5-7 zones e.g. 1. Open plan downstairs, 2. Hot water cylinder, 3. master bedroom, 4. dbl bedroom, 5. single bedroom , 6. bathroom, 7. hall.

My house in being renovated, and I am running new central heating pipes and electrics anyway, so I will never get a better time to do this.

Is there a simple, and relatively inexpensive way to achieve this or to improve from the standard 3-zone?

Thanks,

Sean.

Plombier

Pipe all your rads back to a manifold with electric actuators then a seperate stat in each zone.

yoshytoshy

Theres not much point in seperating a three bed semi with zones in each room. The cost of installing it and maintaining it wouldn't be worth the savings.

Placing one stat upstairs and one downstairs ,would be more than enough. Some houses have rooms the size of the entire upstairs of a three bed semi ,thats where individual zones make more sense imho.
Thermostats on radiators are very effective.

crosstownk

Plombier wrote: »

Pipe all your rads back to a manifold with electric actuators then a seperate stat in each zone.

What cost are we talking about for this?

I assume it would be a wiring & plumbing nightmare.

I do agree with the OP. I've the standard 3 zone set-up but as the upstairs stat is in the landing it will get little or no heat if all doors upstairs are closed. Essentially it then only reach the desired temperature as the heat from downstairs rises.

ReadySteadyGo

Thanks for the feedback so far.

@Plombier - Thanks for that. That sounds like it would do the trick! How do you think the install cost of that would compare to a standard 3 zone system? I guess their would be a good bit more piping. Would the manifold be expensive? Do I need extra pumps also? or can I run this off a system boiler?

@yoshytoshy - I agree that It would be important that doing it is economically sound. As I have to install a new CH system, I thought (maybe naively!) it might be relatively inexpensive to gain a few extra zones.

While searching, I also came across the concept of programmable TRV's which is growing on me e.g. Honeywell CM and Househeat. i.e. I would just have a hot water and a rads zone on the boiler, and use programmable TRV's to zone each room. Thoughts on that?

yoshytoshy

ReadySteadyGo wrote: »

While searching, I also came across the concept of programmable TRV's which is growing on me e.g. Honeywell CM and Househeat. i.e. I would just have a hot water and a rads zone on the boiler, and use programmable TRV's to zone each room. Thoughts on that?

Standard Trv's will control heat in rooms ,to suit your needs. I have my bedrooms set to 3 on the trvs and the rads never come on ,minimal cost and it works.
Sitting room looses more heat ,so I have that set to 4 to compensate for the heatloss.

Get a good boiler and electrical controls and it's money better spent.

Programmable stats/trvs are great on their own ,but in a small house I think more than one or two are pointless.

ReadySteadyGo

@yoshytoshy - Downstairs I'm open plan so a programable room stat and a downstairs zeon will work perfectly.

But upstairs, when it is cold outside (and you therefore need to actually add heat the rooms to get them comfortable), and you want the bedrooms heated at different times, normal trvs will end up heating rooms when they do not need heat, and therefore wasting heat.

e.g. If you want one bedroom warm at 06-07+19-22(4hrs), another warm 07-08+20-2200(3hrs), and another one warm 08-09+22-23(2hrs).

You will end up heating all bedrooms from 06-09 (3hrs) and 1900-2300 (4hrs) = 3 rads x 7hrs = 21 radiator hours.

A room zoned system would require only 9 radiator hours. (half as much).

Another plus of a room zoned system would be the option of "curving" the room temperature to fit the usage say 16 or 17 degrees in the morning just to take the sting out of the air (mon-fri), taking it to 20 during early evening, and dropping it back to 18 for sleeping, and then a different profile for the weekend.

Obviously if all occupants have same waking and sleeping time this is not an issue. But I am likely to rent out rooms in my house, and I would expect different occupancy times.

I've no idea how to put a "cost" on this lost heat.

ReadySteadyGo

a zone for water is a must.

a zone for downstairs open plan living space with a programmable room stat is perfect for my time/temperature/boost functionality. The only other rad on the downstairs zone is in the hall, which I am not too concerned about directly heating at all, So I am happy to use a trv turned down very low/off.

At the moment I have a few solutions for more control of the upstairs rads - not even sure if they all possible in the real world...

0. Standard zone upstairs with a fixed stat in the main bedroom+trvs in other rooms. (I have ruled this out, as other rooms may never get to their desired temperature once the master bedroom is satisfied)
1. Standard zone upstairs with a fixed/wireless stat+boost in landing + trvs in rooms. (not even sure why to bother with a landing stat here at all to be honest, as in practice I think I will turn it up high to ensure each room can get to it's desired temp - but I guess it would be handy as a quick way to limit the upstairs heating in case some of the TRVs fails or are set at 30 degrees)
2. same as 1 with the addition of wired programmable radiator valve in each room, which controls the valve based on time and temperature, and also hopefully the boiler?. Any suggestions for some wired hardware that would do this?
3. Initially start with 1, and later have the option to add househeat or similar programmable wireless sensor and radiator valve to each room. The only missing link here is the ability for each room to turn the boiler on (maybe there is or will be in the future some wireless kit that would also do that?) in the meantime the boiler must manually be set to cover all hours programmed in each room valve. And boost requires the user to boost their room programmer, and boost the stat in the landing.
4. Plumb each rad to a manifold, and wire a programable stat in each room to the manifold valve and some form of relay/multiplexer (to combine the call for heats from each room) before sending them to the main programmer as "call for heat from upstairs zone") - Is their a cheaper way to do the controls here and achieve time and temperature settings for each room?

ReadySteadyGo

I guess to make it economical, one has to know the spend on heat in advance.

I have seen studies reporting 60-80 per cent of energy usage in the home is heating.

Does anyone know a rough annual price for heating the *upstairs* of a house 6 hours a day 6 months a year, assuming a modern condensing gas boiler, good windows (.8u) and decent wall insulation (.27u)

yoshytoshy

Hi ,just in answer to your suggestion of having one radiator on at a time.

It's crazy to have a boiler firing up for just one small radiator. Gas boilers do modulate ,but theres limits to what it can do.

Like I was saying before ,it's really only large areas that you'd call heat for.

ReadySteadyGo

Hi Yoshy,

The smallest bedroom and bathroom would be ~ 1.2kw(2.7mx2.7mx2.5mx.07)
The other two bedrooms would be about 2.1kw each.
The open plan space would be about 5.7kw

The boilers I am looking at will modulate down to somewhere between 4 and 7kw.

Even if it does not modulate low enough, surely it costs less to run the boiler to heat the one required rad, rather than heating 4 rads?