Hi,
I guess most people here have their CH zoned. How many zones do you have: one for upstairs and one for downstairs, or does anybody have something more elaborate?
I guess people here are quite handy and have modified their own CH systems. How common are CH zones away from this group? I don't know anyone in the "general public" that has CH zones.
Do the regs require zoning yet? I guess when they do, zones will become more commonplace.
I don't think I know anyone with zoned central heating. Ours is all controlled off of a thermostat in the living room, with thermostatic valves on the upstairs rads. Not my configuration - and the valves need replacing anyway, as they don't switch off - I'd sooner have them on all rads.
It's all a matter of taste and utility. I have a long thin bungalow, so I need three zones: left right and middle, plus HW, of course. In my case it's because there is no sensible place for a single thermostat and one end gets all the sun-powered thermal gain.
It saves about =C2=A3120 per extra zone to omit them (Valve + Thermostat), = so builders and plumbers typically don't install them.
R.
Ive neded yp with tow primary zones, upstairs and downstairs.
Downstairs is largely UFH and that's split into as many potentaial zones as there are pipes under the floor. mater thermo is in the living troom, with ath aga-ified kitxchne on a sperate sta to prevent that overheating.
Upstairs is all TRVED for the rads and towel rails, and every fan convector ha its own stat.
So its really about ten sub zones!
TRVS are a sort of crude zoning, to be fair. Not very effective, but they help.
We have one zone per room. Motorised valves, switched by relays, operated by timer/stats in each room. The timer/stats could operate the valves directly, but using relays has allowed us to use a 12V system, letting us wire with alarm cable (easy to hide up the edge of architrave until we next re-paper the rooms) and allows for one in the bathroom. The old dual channel timer has become the time controller for the hot water and via a contactor for the immersion heater (normally disabled, but can be used for boost or if a heating fault means that hot water would otherwise not be available).
Too expensive for many people, but we got the timer/stats for £14 each; the valves were being sold off for £20 each when B&Q were changing suppliers some years ago and of course DIY saved a fortune.
We just like the flexibility of differing times and temperatures for each room - especially with young children.
SteveW
I have an upstairs zone and a downstairs zone and in addition the bathroom rad is in parallel to the bypass circuit so is on whenever the boiler is firing. The bathroom rad has a TRV so there is also a small radiator on the landing as a heat sink for the bypass when the bathroom is up to temp.
On Wed, 10 Mar 2010 12:04:58 +0000 someone who may be Robert wrote this:-
Away from DIYers they are not common at all.
Yes, for large heating systems IIRC. Large houses upwards.
Zoning depends on the house. Where solar gain is high north/south is the best form of zoning. Where there is different occupancy ground/first floor is often best (assuming bedrooms are all on the first). Some combination may be best for a particular place.
Oh cmon now. Data bus right round the house, to drive a valve for every heat source and pick up a stat in every room..all controlled by a centralised computer.
In fact, use the mains ring to do the bus, and make em all hotpluggable ethernet type devices..Hmm. I may actually build that one..
So what we need is individually addressable ethernet-over-mains motorized valves and independently addressable thermometers that also just plug into the mains.
then you could dial into your house using your mobile I phone app and make sure the heating was on for when you got there...;-)
Our underfloor heating had three zones upstairs and three downstairs. When I replaced the leaking upstairs with radiators I didn't put zone valves in, but I might sometime. Or replace the TRVs with Honeywell CM Zone ones. Recommendations for alternatives recomended....
One of the downstairs zones could usefully be split in two, but not easily - the heating pipes from that manifold do two rooms, and the southern one is much warmer than the northern one. And another downstairs zone is currently waiting for me to swap an unused valve actuator from upstairs to replace a failed one.
(Fixing the fact that the boiler pump is permanently on is a higher priority than zoning upstairs. In theory it was switched by the thermal store cylinder thermostats, but in practice those do nothing. The zone thermostats do switch the underfloor heating pump (the upstairs ones are off, the radiator circuit has an auxiliary pump just switched by a timeswitch for now (I did try asking about controls here a while back, but no-one seemed to understand the question - professional plumbers who are actually looking at the system get confused by it too, so its not just my description))).
Why are you zoning? More accurate and separate temperature control, or ability to heat only part of house? These have different design considerations.
I designed with upstairs, downstairs, and (downstairs) bathroom. Bathroom is connected directly across boiler, so it's the logical 'OR' of the upstairs and downstairs zones. (Boiler only does central heating anyway, and not hot water.)
Be careful making too many tiny zones - boilers aren't efficient at providing 600W for one radiator at a time, and going to a thermal store is significantly extra complexity and very questionable in any efficiency gain claims.
Nor do I, not even in large houses.
Yes for large houses, but never implemented as far as I've seen in professional installs. I don't think it's something many domestic installers would understand. Indeed, it's rare that they do the electrics/controls anyway - usually get an electrician in to do it IME.
This summer I will fit motorised valve/s to the upstairs bedroom circuit controlled by a timeswitch so that it shuts about 9AM then re-opens about
9PM. Main problem is cost of motorised valve (I'm using 2nd hand ones) and need to lift carpet. Savings should be significant as many days CH is on all day.Much better return than solar cells/wind farms. Not sure why the govt dont push this a lot harder.
On Wed, 10 Mar 2010 18:11:16 +0000 (UTC) someone who may be snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote this:-
Extra complexity, yes. Significant, I don't think so.
You reckon? Simply by avoiding short cycling (and modulation if the boiler has it) it will increase efficiency. The proof of the pudding is the lower gas bills.
On Wed, 10 Mar 2010 19:34:26 -0000 someone who may be "Mitch" wrote this:-
Probably for the same reason that they don't insist on the radiators being resized when a condensing boiler is fitted, so that it condenses for an appreciable time. Modifications to pipework are more difficult.
Three zones, ground, first and second. Strangely, specified by the people who restored the property just before us who cut lots of corners elsewhere.
Two boilers in parallel with no check valves to prevent water going the wrong way through one of them when the pump is stopped. We have only ever used one at a time with the other isolated. Four zones including water, originally using a triple and single time switch with a contactor.
I have replaced the time switches with a homebrew PIC micro based controller that has remote control stations with temerature sensors on a CAN bus. As we are moving this will be replaced with simple time switches again as I don't want to have the responsibility for it. The HIPS inspector was well impressed and gave us some credit for the zoning and control in his report :-)
Pete
Modulation isn't an issue. Short cycling can be, but needn't be (more intelligent boiler firmware control can eliminate it).
Additional pipework and storage facilities will result in additional losses. Also much greater volume of water to be heated before heat is available to the room, and that larger volume of heat to be lost when heating is no longer required.
when compared to a similar installation but without a heat store, but also installation and maintenance costs over lifetime of system. It is a failure of KISS, for gains which are not clearly commensurate; in some cases they may be, in other cases they won't be.
On Thu, 11 Mar 2010 10:46:03 +0000 (UTC) someone who may be snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote this:-
And who was it who said, "boilers aren't efficient at providing 600W for one radiator at a time"?
Assuming the system is designed properly the additional pipework is negligible.
While no insulation is perfect, the sort of insulation provided on a thermal store is fairly good. One should only drop by a few degrees overnight. As long as that heat goes into the building this is no great problem.
You don't understand thermal stores. Heat is available almost instantly in the room, as it was heated before heat was needed in the room. Depending on how much heat is taken out and the initial conditions, at some tome the boiler will fire to recharge the store.
Thermal stores are very simple. An extra pump and a few control elements are just about it. An advantage is a simpler boiler, which is less likely to go wrong, no need for modulation with a thermal store.
Well yes, in some cases the gains are worth it and in other cases they are not. That is where proper design comes in, if the gains are not worth it then the designer should go for something else.
Is that three or four zones? I'm never sure whether HW counts as a "zone".
Why do you say they are not very effective? Is it because they are too close to the radiator?
John's reply said his valves didn't turn off. Is sticking a big problem? I think I have a TRV that doesn't switch off (and it's not because the room is cold). Could the pin be stuck? I thought they stuck off, not on. Can they fail either way?
Was this a new build? It doesn't sound easy to retrofit because you would either have to run a lot of new pipes if all the valves were in a central location (by boiler or in airing cupboard?), or if you have the valves local (under the floorboards?) wouldn't you need to run masses of wire?
Once it is in place though, it sounds very versatile and allows you to only have heat where it is needed and each room at its own temp, which must help with fuel bills.
My only concerns would be if each room has its own stat, do the children turn up their stats too high or have the heat on and their windows open and if they are programmable stats, isn't it annoying having to program a dozen of them?
Having everything controlled by a central computer, as another poster suggests, sounds a good idea. I'll have to learn about PICs.
That is what my experience suggested but since 4 channel programmers seem to be on the shelf at B&Q and Screwfix, I wondered whether things were changing.
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