Whilst trying to sort my neighbours heating issues (10/16) I have noticed a few points that I'd like to run past the panel please.
The 'heating' temperature is currently being set by the boiler stat. Would a room stat be a better way of doing this and if so did I see there were wireless versions about (and if so are they any good)?
The rads currently sport thermostatic valves but they say they don't work. Would it be worth replacing them (some) with new models, especially for the bedrooms etc? Are the new valves likely to line up with the old pipe work?
I noticed the flow into the indirect cyl coil is in 22mm (or maybe
3/4) whilst the return is in 15mm (with a 15mm 'by-bass' ). It then looks like the 15mm return from the water cct goes back to the boiler and joins the 22 return from the heating cct somewhere behind the boiler, what's that all about?
They are only an old retired couple so anything I do will be for them as a favour, shouldn't cost too much materials wise, ideally save them energy and be simple to use. ;-)
It sounds like there might be a few issues about the hot water pipe size - my view on the controls are - Yes a room stat would be a good idea - but is the boiler a back boiler without a diverter valve? If so then you may also need to consider a tank stat and a valve in the indirect feed - both wired back to the boiler so it turns off if neither stats are demanding heat. Could be complex. These improvements have a habit of ending up costing more than anticipated and you might feel you have egg on your face.
The boiler is a Netaheat 10/16 Electronic (wall mounted balanced flue) and it does indeed have a diverter valve, cylinder stat and basic timer (all in the airing cupboard).
I don't believe it will be too difficult to include a room stat into the cct (there is a junction box under the timer / controller) once I figure out what's what etc.
So, as the wiring route from room stat to controller isn't easy, are wireless stats reasonably priced and reliable etc (in this ever increasing radio noise world) ?
All the best ..
T i m
p.s. The rad stat valves are made by 'Temtrol'. Are they still about, were they any good?
Are they actually adjusting the boiler stat on a day to day basis, depending on the weather? This is a fairly crude way of controlling room temperature - and will be upset by any change in outside temperature.
A room stat would be a good idea. These come in 3 basic versions (I'm sure someone will think of more!):
Simple mechanical stat with a knob to turn, and a built-in bi-metalic switch
Electronic programmable stat with LCD display and programming buttons
Wireless version of (2) enabling the switching part to be remote from the sensing/display part
Wireless stats work fine, but are more expensive than their wired counterparts. However, if your neighbours are in any way technologically challenged, they'd be far better off with a simple mechanical stat.
The radiator in the room where the room is fitted shouldn't have a TRV on it. If it has, remove the thermostatic head to avoid any 'fight' between the two types of stat.
Have you verified that they don't work? What is the problem? Do your neighbours know how to use them? If you *do* replace them, you may find slight variations in pipe connection positions from type to type - and will need to find some whose critical dimensions are are close as possible to the old ones.
Dunno! I assume it's a fully pumped system rather than pumped CH and gravity HW? Are there any motorised valves? If so how many, what type (2-port or
On Tue, 23 Jan 2007 14:00:59 GMT someone who may be T i m wrote this:-
Yes. It needs to be situated in a room that represents the rest of the house. A north facing room without supplementary heating is a good choice.
There are. They cost more to do the same job. In my view running a cable is a better choice and spend extra money on a programmable thermostat with optimum start (and ideally optimum stop) which will save on running costs.
Why don't they work? Are they perhaps turned up fully and thus never go off? If you take the head off can you waggle the plunger up and down?
It is a method of restricting the flow into the cylinder so that it does not get most of the hot water. Is there a motorised valve to control flow of water to heating and cylinder?
Depends on how they don't work, and how much it bothers them I guess. Obviously if the rads failt to get hot then they need sorting.
You may be lucky! In reality it ought to be possible to find something at least close to the originals. How close it needs to be will depend a bit on how rigidly the pipework is held in place - emerging from concrete floors being the least tolerant of movement.
Which bit, the merging of returns or the 15mm section?
No, I believe they turn the heating on or off manually as desired.
Yup. these are very simplistic people. ;-)
Understood ..
Ok, so they do exist at least ;-)
Well, 'she' seems to be the one who takes control in such matters and would be able to comprehend the procedure if explained gently .. and maybe in time get 'him' to understand what to do also.
Understood.
No, 'They don't affect the temp of the rads' and short of turning them fully on and off (and noting no change) I think so? ;-(
Ah ok, that was sorta what I though might be the answer.
Are there any motorised valves? If so how many, what type (2-port or
Ok, from what I have briefly traced out in my mind whilst trying to sort the boiler problem and from memory it goes like this.
Boiler on kitchen wall, flow goes up into the airing cupboard in the bathroom (above and over a bit) and into what I guess is an air trap (stubby copper manifold thing about level with the top of the cylinder), then the expansion pipe continues up into the loft (in
22mm). From the manifold it goes back down via the pump to the common of a 'T' shaped motorised valve. One leg goes off and down and presumably to all the rads up and down. The other leg goes straight into the top of the cylinder coil. The 'return' from the cylinder comes out in 15mm and then goes downwards but before it disappears from sight is cut by a an equal 'T' with what I believe is a bypass cct going back to the input of the motorised valve. There is a 15mm gate valve in the middle of this bypass pipe. I don't think I can see any of the 'return' from the rads in the airing cupboard area but can see it coming back into the boiler 'plus' this little 15mm pipe from the cylinder return?
I have not mentioned the cylinder hot water draw off or cold feed but they are all there and accounted for.
The electronic mini timer (3 sliders, HW, Heating and the timer) is showing signs of wear being uses to 'manage' the above for the last 'X' years (where X could be as much as 20).
Ok, well along their ground floor Nth face is front entrance and kitchen (all open plan). There is a small rad in the hall bit and a larger double one in the kitchen. Then they normally have the door open through to the 'through lounge' running E-W across the South of their house and I believe they have a largish (5'?) double rad in the lounge. One half of the South side is covered by a nice consecratory.
The stairs lead directly off the entrance hall and I believe there are small rads in the three bedrooms (1 big 2 small) and bathroom.
Ok, well depending on where this stat ends up the wiring could be easy (without damaging the decoration) or hard.
I felt the plunger move on the one I turned up and down but that's all I've done so far.
Yes. And I know that works when running heating only (water branch cold) then turning water to continuous on timer and feeling it go hot ..
Only as in their willingness to take on any major changes where they can't see a reason and spending power of a retired couple who have had to support some wayward offspring ..
Only lie they seemed quite happy sliding the controller switches on / off manually for the last X years (to the point where it now feels 'worn') ?
Nope, they all get equally hot equally quickly (AFAIK).
From what I remember most pipe work is fairly 'external' and nothing that would phase me particularly should I have to modify positions etc (just would prefer not to have to).
The 22mm flow *into* the cylinder and 15mm *return* I guess (unless that's part of the 15mm bypass thingy. The bypass looks like it 'bypasses' the motorised valve to some degree).
OK, so it's a fully pumped system with a 3-port valve. The valve could be a diverter valve which feeds either the HW or the CH but not both together, or it could be a mid-position valve which allows both to be on at the same time in addition to separate operation. If it's a diverter, they have a W-Plan system and if it's a mid-position valve, they have Y-Plan.
Schematics for both these plans (and others) - plus wiring diagrams - can be found at
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on which it is, a room stat would need to be connected either between 4 and 7 or 4 and 5 in the junction box. There is probably a solid link at present which will need removing.
If you install an electronic programmable stat (either wired or wireless) that will do all the timing for the CH - which needs to be left permanently on at the main timer. Such a stat does have several advantages over a pure mechanical stat, such as:
the ability to programme different temperatures at different times of day (or days of week even, if 7-day model)
more accurate temperature control, with less hysteresis
acts as frost stat even when 'off'
[optionally] provides optimum start - where *it* decides when to switch the heating on in order to get the house warm by a specified time
extra features like holiday mode, where you turn the heating off for X days and have it come on just before you return
BUT, these stats are bit more complicated to drive than a simple one with a knob to twiddle - hence my earlier warning. If your neighbours can cope with a mobile phone - including maintaining their contacts list etc - they'll probably be ok. Otherwise, I'd stick with a simple one and forego the advantages.
With regard to the 15mm pipe, it was not uncommon years ago to have a pumped HW circuit in 15mm (or 1/2") - on the basis that (before fast recovery cylinders were invented) a 1/2" pipe could carry heat to the cylinder as fast as it could absorb it. Whoever installed this particular system seems to have done this in the return part of the circuit - the flow side being common with the CH anyway. The CH and HW returns need to join *after* the last radiator's return connection - so maybe that necessitates taking it almost back to the boiler as a separate pipe. I'm not quite sure why they need a by-pass *unless* the boiler controls the pump in order to provide pump over-run - in which case there *may* not be any other flow path when all the TRVs are closed - hence the need for the by-pass.
Being retired and both having treatment for one thing or another they are pretty well housebound atm so a straight daily time schedule would be sufficient atm.
Ok .. The boiler has a cast iron heat exchanger so doesn't react very quickly.
Like our electric storage rads do (we don't have CH).
They (he) feels the need to turn everything off when not being used. That's ok for the TV etc but this also includes the CH timer and bedside clocks during the day (yes, resetting the time every night)!
Understood .. looks like 'she' will be configuring it all then ;-)
Understood. And the valve is 22mm along with the cly and only 3" away ;-)
Oh, ok ..
I don't think this model does (but the 22 does). Thanks again for all your feedback Roger.
Ok, bottom line, what sort of money are we talking about for a 'conventional' room stat, a basic wireless stat (if there is such a thing) and the sort of thing you describe above please (ball park etc).
If you have a current Screwfix catalogue (No 85) have a look at pages 386/7.
The cheapest mechanical stat is 12 quid.
It looks as if you can now get a non-programmable electronic one for about
17 quid.
The cheapest programmable one (wired) appears to be about 43 quid.
Wireless devices are in the region of 80+ to 100+. [It loooks as if you can now get a non-programmable wireless stat for about 86 quid].
If you go for the 17 quid model, you can buy a lot of cable and small white trunking (to conceal/neaten exposed cable) for the near-70 quid difference!
On Tue, 23 Jan 2007 14:00:59 GMT, a particular chimpanzee named T i m randomly hit the keyboard and produced:
I bought a basic Drayton wireless room thermostat for my mother's house about two years ago for £20. The battery powered thermostat is in the Living Room, and the receiver is next to the programmer, up a storey and through a brick chimney breast. Seems to be working OK. It's still on the original set of AA batteries.
It would be worth checking these before taking action to replace them - all they can do is set the temperature in the room if there's enough of a heat output from the rad, which depends on other factors. A quick check is to remove the head and see if the operating pin moves down and up freely
- it should push down with a finger and return under spring pressure. Better makes may have a repair kit available if it doesn't.
If they aren't working, yes.
Depends. If a well known make, possibly. Shed bought ones might not have direct replacements as designs change. Look at the lockshield valves and see if they are the same sort of fitting and pipe lengths, etc. If so replacements should be easy to fit.
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