AuthorTopic: Central heating thermostats.  (Read 4846 times)

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Offline muddyjames

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« Reply #30 on: October 09, 2007, 18:06:36 »
Quote from: "Lyndsey731"
Go on then I'll have a go :lol:

In parallel when the downstairs stat switches off the upstairs is still in circuit so the boiler stays on continuing to heat both up and down.


That is what I want  :D I can turn all the rads off downstairs except on very slightly to give some heat out just to keep the frost off. This way I can use my bedroom to tweek temp up n down just to the rad in my bedroom and bathroom. When guests come round I can turn downstairs up and open up lounge rad valve. Guests go home and back to bedroom stat I go.

Quote from: "Lyndsey731"
My solution, keep the stat on low to heat the areas that you want background heat in, turn off the rads where you don't want heating and spend £50 on an electric panel rad with integral stat to sit in your bedroom.


But surely this uses alot of leccy? Gas is cheaper than leccy is it not? I cant get my head around the most complicated bills in the world EVER.

Quote from: "Lyndsey731"
As for your towel rail you can get electric ones but to the letter of the law it will be subject to Part P of building regs  :wink:



Would a water one not be easier to plumb in as it is just going to the other side of my door (not enough room for a rad though) and would involve 2 floor boards to be pulled up and 4 carpet tiles!!??
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Offline V8MoneyPit

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« Reply #31 on: October 09, 2007, 18:21:46 »
Quote from: "muddyjames"
Quote from: "Lyndsey731"
In parallel when the downstairs stat switches off the upstairs is still in circuit so the boiler stays on continuing to heat both up and down.


That is what I want  :D I can turn all the rads off downstairs except on very slightly to give some heat out just to keep the frost off. This way I can use my bedroom to tweek temp up n down just to the rad in my bedroom and bathroom. When guests come round I can turn downstairs up and open up lounge rad valve. Guests go home and back to bedroom stat I go.


That's not what he said though! When either of the stats are still in circuit the boiler will provide hot water to all the rads. So it won't do what you need. You need to have 2 separate water circuits to be able to switch each one separately. Or thermostatically control each radiator separately.
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Offline Lyndsey731

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« Reply #32 on: October 09, 2007, 18:27:06 »
I do understand what you want to do, but unfortunately it wont work. The room stat doesn't dictate the output of the boiler, it just lets the boiler know when the room is warm enough and the switches it off. Just because you want downstairs at say 10° and upstairs at say 20° the boiler can't put out two different water temperatures so if the downstairs stat is off and the upstairs is on both get 100% heating. With a zone valve when downstairs is at temperature the valve closes and sends everything upstairs, when downstairs gets cold the valve opens again allowing the hot water to flow through the downstairs loop again.

As for electric heating it wont use much juice for a small room and it would certainly be cheaper then what you have to do at the moment.

A water towel rail would be easier in your case by the sound of it but you will still have the same problem.

Gav

Edit Steve your a faster typer than me :lol:

Offline V8MoneyPit

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« Reply #33 on: October 09, 2007, 18:39:57 »
Quote from: "Lyndsey731"
Edit Steve your a faster typer than me :lol:


Maybe so... but I'm learning a lot here  :D I took one look at the plumbing in the airing cupboard and shut the door.... pipes and valves everywhere  :roll:   Far too complicated for my single brain cell to cope with  :lol:
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Offline muddyjames

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« Reply #34 on: October 09, 2007, 18:49:29 »
Quote from: "Lyndsey731"
I do understand what you want to do, but unfortunately it wont work. The room stat doesn't dictate the output of the boiler, it just lets the boiler know when the room is warm enough and the switches it off. Just because you want downstairs at say 10° and upstairs at say 20° the boiler can't put out two different water temperatures so if the downstairs stat is off and the upstairs is on both get 100% heating. With a zone valve when downstairs is at temperature the valve closes and sends everything upstairs, when downstairs gets cold the valve opens again allowing the hot water to flow through the downstairs loop again.



Sorry guys. I am really bad at describing things and have no way of thinking how to describe it in a drawing either :(  :cry:

I only want the heating to kick in downstairs if say I am away for a weekend and it has a really cold bite outside and then the heating will kick in from say 5c and go up to 10c. Hopefully upstairs stat would kick in too but as cold air sinks I guess downstairs would freeze faster?

I'm not after 2 different heats up and down stairs. All I want is my bedroom and bathroom warm and when guests are here the whole house at same temp as bedroom and bathroom.

I don't care about what temp the lounge is or kitchen as I dont go in my lounge at all and my kitchen for all of about 5-10minutes a day and that is on my way to work after making me lunch box for the day so I can go and leap in my car and get warm again!

I wonder if this might help me describe it better?
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Offline KILTY

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« Reply #35 on: October 09, 2007, 19:49:06 »
Not cost effective-you would have to alter the pipework and seperate the two loops/areas you want to control,fitting an electric zoning/control valve on each one - controled by your thermostats

The "best practice" is to fit thermostatic radiator valves to all but one rad - eg - hall and fit a room thermostat in that area to act as a maximum temperature/boiler interlock - and turn down the areas you dont use
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Offline Lyndsey731

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« Reply #36 on: October 09, 2007, 19:59:58 »
ok first of all forget the two stat thing, without two loops of pipe its not happening :cry:

What you could do is a mix of all the comments so far:-

Leave the stat where it is set to say 19 turn all the TRV's downstairs right down, if you dont have TRV's just shut the valves down quite far it wont directly control the temp but it will send the hot water off elsewhere (path of least resistance).
Make sure your bedroom and the bathroom have no TRV fitted or are fully open, you must keep an open circuit or you will blow the system.
Next set the boiler out put temperature to level which gives you a comfortable level of heating in the bed and bathroom.
What should happen is that the stat will always be calling for heat, the downstairs rads will give out a little heat whilst most will go to upstairs to the bed and bathroom but when the return water temperature at the boiler hits the boiler output temp it will turn the boiler off. Once the return temp drops the boiler will fire back up.

Not the best solution but to be honest the only way i can think of with your set up.

As for turning on when it's very cold you will need a frost stat that someone mentioned they had in their garage earlier.

TBH in my opinion still cheaper to get a panel rad :lol:

Good luck

Edit: god my typing is getting slower, apologies!

Gav

Offline muddyjames

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« Reply #37 on: October 09, 2007, 20:33:48 »
just had a whacky thought. how about I move the stat to my bedroom? 1 stat just instead of being in the coldest part of my house it is in my room?
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Offline BigSi

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« Reply #38 on: October 09, 2007, 21:07:43 »
Basically you need to have your heating system separated in to zones. Adding another room stat in parallel, will only bring in the central heating side of the system when the first room stat drops below its temperature setting. Remember a room stat is only an on/off switch. You would also have a cylinder stat that would operate to give you hot water.

Also remember that any electrical work you do, might be classified under Part P of the building regs. Unless your registered, you have to notify the LABC of any proposed electrical work (ie running a new circuit). My advice, get an electrician as any work done needs to be tested and certified.

Bathrooms are classified as special locations, so ANY electrical work in this area (ie fitting a towel rail), is notifiable under Part P of the building regulations. This also includes kitchens and the outdoors.

If the room stats are wired in series then when the first one reaches its min temperature setting it can only operate the boiler if the second stat is also closed.

If wired in Parallel, as soon as either stat falls below its min temperature setting, the circuit will close brining in the boiler. The problem with this, is that it would also energize both side of the second room stat. And if both areas are cold to start with, then the boiler would not turn off until the largest area is heated (unless this stat is turned right down), regardless if the smallest are has reached its temperature or not.

I’m no plumber, but its Thermostatic rad valves that you need.



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Offline MuddyMike

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« Reply #39 on: October 09, 2007, 21:30:54 »
Okay. as far as I can see your plan would work.
 
First check if the thermostat has three wires or two (excluding earth)
Second buy thermostat with same wiring.
Extend wires from existing stat to new stat wiring everything in parallel
 
Now you are set.
 
Situation one. You are home alone.
 
Turn downstairs stat to low, turn off downstairs rads, turn bedroom stat to required temp, turn bedroom rad (and towel rail once fitted) on.
 
Result. Boiler will run when heat is demanded by bedroom stat, bedroom and  towel rail will be warm, other rooms will be cool.
 
Situation two. You invite Mud Clubbers to stay.
 
Turn downstairs stat up, turn rads in required rooms on.
 
Result. Boiler will run when heat called for by downstairs stat, all rads that are turned on will get hot.
 
I would recommend a time controlled thermostat, you can then pre set different temperatures for different days/times of day. Good investment at about 21quid.

As for the legalities of doing this yourself, I am no expert in part P but if you are allowed to DIY a spur socket, this must also be allowed.

Mike
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Offline muddyjames

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« Reply #40 on: October 09, 2007, 21:35:13 »
Hey Mike.

Are you a plumber by any chance?? If it is a 2 or 3 wire one what is the difference?

The way you described it is so much more in plain english than I can do. Cheers.
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Offline MuddyMike

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« Reply #41 on: October 09, 2007, 21:52:10 »
Nope neither plumber or electritian, just a knowledgable DIY artist. I am not 100 sure of the functional difference between two and three wire thermoststats but know from experianece. that you must use the same. The third wire is something to do with reducing sparking on the contacts when switching. I have added a second thermostat at home to achieve similar results.

Mike
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Offline freelanderpx54

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« Reply #42 on: October 10, 2007, 01:08:28 »
Quote from: "V8MoneyPit"
So I guess if you turn the boiler down it would be on more often to maintain temperature? But if your radiators are also turned down, they wouldn't release as much of the heat that the boiler puts into the water. So the boiler kicks in less. Is that right?


Pretty much. Don't forget that if you have "cold" rooms, these will create draughts and reduce the ambient temperature further.

Go for TRV and turn the boiler temperature down. It is more efficient to keep your place at a consistent warm temperature than it is to keep heating it up from cold

Offline SimonHarwood

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« Reply #43 on: October 10, 2007, 01:28:19 »
Quote from: "muddyjames"
just had a whacky thought. how about I move the stat to my bedroom? 1 stat just instead of being in the coldest part of my house it is in my room?

Except for a like-for-like replacement of a thermostat, zone valve or damaged cable, any work on boiler control wiring is notifiable to building control under Part P of the building regulations.
Should you wish to go to the trouble of the pipework and wiring alterations, there is nothing to stop you having multiple zones in the heating system each controlled by a separate room thermostat. (Thermostatic radiator valves are very good.)
Gas Main works are like ants... You never see them in the winter, but once the summer arrives they appear everywhere.

Offline mc123

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« Reply #44 on: October 10, 2007, 08:44:18 »
Last thing I expected to be talking about on here!

http://www.thermsaver.co.uk/heating_controls/rf_program_stat.html

At home we use one of these.  

Use TRV's and turn them down in the rooms you do not use and move this to where you spend your time.

Simple, flexible and no wires to run!

not cheap though but there is always eBay.

Offline muddysteve

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« Reply #45 on: October 10, 2007, 12:30:37 »
if it were me i'd go for TRVs and a programmable stat.

no point haveing 2 stats wont achieve what your after. if your gonna turn off all the rads apart from the one in your room then moving the stat into your room would have an affect.

or do what i've done, turn the stat down to about 19deg and leave well alone, has saved me a fortune in gas bills and if i get chilly i just put a jumper or electric heater on
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