Domestic CH - to zone or not to zone...

[Mike Barnard]

Hi all.

Any CH design guru's aid me in my small dilemma please?

I have a 1960's mid terrace Wimpy (spit) three bed house. It had no CH at all untill a couple of years ago when I put a new combi boiler in [1]. I also put a couple of rads in. It was not a complete system, DHW was what I needed mostly. Now the time has finally come to finish the job.

The dilemma is whether to zone off the rear two rooms upstairs. The bathroom and bedroom 2 are north facing and in winter they can be much colder than the rest of the house. The thremostat and timing controls are in the open plan lounge; see description below. If the lounge is nice and toasty, then the thermostat will not be telling the boiler to fire up. Therefore the water in the pipes will not be heated and under circulation. No matter how far the TRV's in these rooms open they will recieve no heat.

Thoughts:

If I put a zone in to supply heat for these rooms its a lot more pipework and electrics to try and hide.

If I'm doing these two rooms why not all of them.

If I do all of them am I going to lose heat when the upstairs is off and downstairs is leaching up?

What else?

Layout is...

Front is facing south, rear north. 1 mile from the sea.

Front door opens directly to the living room.

Ground floor split into just two rooms: - a living room to the front - a dining room / kitchen to the rear

Open staircase from the living room to a landing.

Off the landing at the back is the bathroom and bedroom 2, (my 5yo sons.)

Off the landing to the front is bedroom 1 (ours) and bedroom 3 (used as a study.)

Radiator with no TRV in the lounge as the controls are here by the stairs. Radiators with TRV's in all other rooms. Heated towel rail in bathroom.

Thanks for any eyeopeners.

Mike.

[1] Worcester Bosch Greenstar R35HE Plus. What a mouthful. As a part of putting in a new kitchen, losing an airing cupboard and a wall and associated HW tank and plumbing.

[EricP]

Well I didn't "zone" and bitterly regret it, so go figure from that.

Do any work you think will improve the system. You will think of plenty when it's too late.

[JoeJoe]

Same here. Feeling rather silly heating the whole house when upstairs is empty. Also, we find it quite difficult to avoid overheating the kids bedrooms in the evening when they are already in bed and we are still downstairs (bedrooms were added much later and are much better insulated).

[Roger Mills]

With a properly designed and balanced system (with radiators of an appropriate size in each room/space to balance the heat loss - and with the lockshields adjusted to give the same temperature differential across each radiator) there's no reason why one room should be significantly hotter or colder than any other.

Zoning comes into its own if you want to heat different parts of the house at different times. Otherwise there's not all that much point. If it's easy to do, do it anyway - because it gives slightly better control over different areas (with a room stat for each area) - but if it's a pain, plumbing-wise, don't bother.

[NoSpam]

... snipped

I re-did our heating a while ago and split it into 3 zones: downstairs, upstairs (less bathrooms), bathrooms+airing_cupboard+workshop. There were a number of people saying it was a waste of effort because of the open staircase. In practise it's been great. If I'm working at home during the day I have the downstairs heating on and the upstairs stays cold. The only regret is that I didn't add a fourth zone for just the office.

Dave

[The Natural Philosopher]

Mike. Its a contstant dilemma..

Ny feelings are as follows. First of all Radio stats are not THAT expensive and save a lot of wiring, and TRV's are even cheaper.

What might be worth doing is adding - say - trv's to everything, and plumb in a bypass loop, and then put a radio stat in the coldest room so that at the least, the heating would stay on till that one was warm..you could simply parallel the output of the existing stat and the radio stat.

That is the minimum of plumbing/wiring work: Ideally stats everywhere feeding zone valves all wired back to the boiler is what you want, but in practice its a hard way to retrofit stuff

The problem with the system I have described is when e.g. the radio stat is set to a higher temp than the TRVs in that room..perhaps the answer is to not have TRV's in that room at all..but then how to turn that room down?

I don;t think there is a perfect answer..you will have to juggle the complexities yourself

[The Natural Philosopher]

There speaks a man of theory..with respect Roger, in the real world, in my north rooms when the north wind blows, so does your theory. MUCH more heatloss from them then...

If I had my time again I'd zone every single room. With a motorised valve, and run a shitload of cables back to the timer and pumps etc.

We have a lot of rooms we don't use all the time, and it would be far more economical to simply flick a switch and have them go to 'frost stat' settings when not in use.

[The Natural Philosopher]

My office has so many computers in it, plus a PABX and a dist amp for TV, and canners/printers/hubs and routers..that it stays toasty warm whatever the weather.

I agree that the more zones the better, frankly. Energy costs are rising and it is starting to be a lot easier to justify the initial outlay.

[Roger Mills]

It would certainly be nice to have an S++++ system, with a programmable stat in every room - so as to be able to heat each room only when needed. You could probably do it without too much plumbing by using (don't know the correct description) things like TRVs with little heaters in them to turn individual rads on and off by remote control. Would need a lot of wiring though, and I don't know whether these things have secondary contacts which close when the valve is open - like a proper 2-port zone valve.

Such a system would be a nightmare to programme though unless your room usage followed a very regular pattern. Even then, you'd have to tell each individual stat about things like going on holiday for X days. Really needs to be programmable from a single point - with the ability to apply global settings to all stats in one go - but I'm not sure how to go about that. I don't really want to run a dedicated PC *just* the operate the heating!

[Lurch]

On Wed, 27 Jun 2007 19:46:29 +0100, "Roger Mills" mused:

You can get mini valves that can be fitted to each rad. Not exactly sure where you would source the as I've never looked tbh.

You can get commercial heating controls that could do all that with relative ease, and mostly low voltage for sensors in the rooms rather than programers.

[John Rumm]

One simple solution would be to change the stat for a programmable wireless one and situate it in the cold bedroom. Balance the system so that all is well when there are no external influences such as cold north winds etc. Fit TRVs everwhere else. That way the stat will call for heat until the coldest rooms are heated, and the TRVs will prevent the warmer rooms overheating.

[Ed Sirett]

It's probably not worth zoning. What you need is to make sure that the hot area have TRV's and the coldest area doesn't.

If you can make sure the hall way is the coolest area then you can have the thermostat there where it is convenient to put on/off when you come in/go out.

[fred]

In article , Mike Barnard writes

Highly recommended :-D

[Graeme]

In message , Mike Barnard writes

I cannot answer this from a DIY perspective, because I didn't do ours, but, having had it done, I think it is wonderful. We have four entirely independent timers, controlling the heating for three areas, plus hot water, all powered by a conventional oil fired boiler. Different parts of the house are heated at different times, to suit our needs. The times can be overridden, of course. Different times for each day of the week, if required. Yes, there are TRVs on the rads, which help, and in theory we could run around adjusting them, but who does?

The only downside is reminding the family that hot air rises - it is fairly pointless having just the downstairs heating on, with all the bedroom doors wide open :-)

[John Stumbles]

Honeywell does a system with some sort of motorised rad valves (bulky and look s*1t IMNSHO). I don't know how they control it all.

Some moons ago I adapted TRVs by glueing PCB-mounting resistors onto the sensing elements so that by applying 12V to the resistor the valve would turn off. I planned to control it all by some custom controller, but never got the Tuits to make it happen :-(

[Mike Barnard]

Thanks for all the inputs. Excuse me if I don't reply to each post individually.

I certaintly agree in the idea of zoning in larger houses, but this is a small 3 bed terrace house. No room at all to supply pipework to each rad! And I'll have to cross many floor joists so I don't want to cut too many pipe holes in either.

So, a couple more questions if I may.

1. Can I have a common return to the boiler or will that cause problems?
2. Are there any websites that show the theories behind zoning? Yes, I have googled and found many sites seling valves, but no tech guides. Nothing in the FAQ either.
3. Should I just do the two north facing rooms?
4. Or three zones... North facing up, south facing up and downstairs?
5. Or one zone up, one down...
6. What size pipes can I get away with if I'm only doing a couple of rads?

Anything else of a practical nature? Regs?

Again, many thanks.

[fred]

In article , Mike Barnard writes

Although I have chosen to centralise the controls and run separate feeds (1 feed/return pair per room) there is no need for you to do the same, you can run a live backbone throughout the house (2 pipes) and place the controls where they are needed. I would suggest though that you make the controls accessible with the minimum of fuss as there will be a time when you need to access them in (and without) anger. If you can make splits off the backbone in places like airing or other cupboards then do so. Be sure to insulate the backbone feed and return (at least) as there is no point in heating the rest of the house if you're just fending off a bit of winter chill in the master bedroom overnight.

Separate paths for feed and return can run into problems but see above for the alternative.

I don't think so, nobody does this, they think it is too hard.

4 zoning would seem like a reasonable split, 2 up & 2 down. Reasoning downstairs being why heat the kitchen at all when you're watching telly? Upstairs is probably less in need of a split but it shouldn't be too hard to do. Separate zones really are superior to the sort of results you get with TRVs.

Depends how big the rads are of course :-), but 15mm to 2 rads off a

22mm backbone would be safe.

Each room needs a control, whether it be TRVs or stat.

Do it, you won't regret it.

[Frank Erskine]

I *love* (real) vanilla :-)

[fred]

But Plusnet is that crappy frozen vegetable whey vanilla that Tesco sell in blue striped gallon tubs, bet you wouldn't touch that ;-)

[auctions]

I'm looking at doing exactly that in a project - using actuator valves and individual room stats. It's not that hard - an actuator on every radiator instead of a TRV. Each one links to a thermostat in the room and all the stats link down to a wiring box. I'll then use a central controller from (their stats look good too, but I'll use different actuators. The ones for under floor heating work - they fit onto a TRV body)

Looks like an ideal system. It's not that cheap, but the plumbing is done as a single zone, so there is a saving there, and the wiring is simple enough. Can be done wirelessly, but that puts the price up.

A