imlach

Hi,

Recently had a new central heating system installed, but feel the thermostat fitted in the hall is not switching the boiler on/off in a very efficient manner.

All rooms except the hall have the valves with 1-5 on them (sorry, don't know their technical name!). The radiator in the hall has no such valve.

The thermostat is mounted on the wall in the hall. Now, it seems to do it's job sort of ok (ie, as temperature gets to set level of 20C, it switches the boiler off). However, the temperature seems to drop FAR below 20C before it switches the boiler on again. This leads to a house where the temperature fluctuates between warm & almost chilly. I just want an almost uniform temperature, but without leaving the boiler running all the time (as suspect there is no need). Just need the boiler coming back on a bit earlier (ie, after 15 minutes instead of 30 mins typically).

Is there a problem with the sensitivity of the thermostat (or is it cheap crap), or is this normal?

Can you get controllers where you can adjust the thresholds etc???


[Edited by imlach - 10/29/2002 3:45:18 PM]

carl

It's called hysteresis, and it's designed so that the boiler isn't continually fluctuating on and off.

If it's an old thermostat, it may be that one of the bimetallic strips is knackered/lost its elasticity/etc.

imlach

It is a brand new thermostat (rotary dial variety).

I realise the system has to have some form of hysterisis to stop the boiler going on/off to often, but in my case, it switches the boiler off for 30 mins or longer, whereas turning it back on after 15 mins would be more efficient as less temp lost???

carl

You would have thought so

imlach

Maybe this is the answer to my problems .......

http://www.plumbworld.co.uk/acb/showdetl.cfm?&DID=10&Product_ID=1622&CATID=45

[Edited by imlach - 10/29/2002 4:15:35 PM]

father_jack

The answer to your problem is getting out more

imlach

Father Jack - heating a detached house in the far north is pricey as I am finding out!!!

£16/week on gas bills in this cold weather by the looks of things :-((((

How is your building for heating? At least you have someone below you generating some heat....

TIFF-C20WTH

Turn your gas meter around or get a new one to put on over the winter

Reffro

You'll have to bear with me with this, but it might be off some help.

The valves all your radiators have on them except the hall radiator are controlling the temperature in those rooms, which is what they should do. The one radiator in the hall will blast out as much heat as it can whilst the central heating is running, whilst the temperature controlled radiators will be regulated by the setting on the valve.

Do you have the radiators in all rooms set for maximum temperature?

If not that may be your problem. The radiator in the hall will blast out heat in the hall way until the wall thermostat says otherwise. But if all the radiators in other rooms aren't on max heat they will not be heated up to the same extent. Therefore these other rooms will be already cooler when the heating switches off.

But in the meantime the hall has had a massive blast of full heat and will take a good while to cool down, as the radiator in there will be releasing heat for some minutes after the boiler has switched off.

Try setting the radiators in the rooms you use the most onto their full heat settings, and you should help to even out the temperature differences between these rooms and the hallway. Set the wall thermostat to the temperature you want in the rooms not just the hall way, and you should avoid feeling chilly whilst waiting for the boiler to restart as the room cools.

That's how we run our heating, keeping it snug in the living room, hallway, kitchen etc, but just a bit cooler in the bedrooms.

scooby nutter

Do away with the Room stat and put a Thermostat rad valve on the hallway rad,like the other rooms.more economical as each room is heated to your desired setting on the rad valves..

had a good one today,a room stat in a kitchen(small)!!
everytime the woman cooked she complained that the heating went off !!!!

Cowboys



Duncan corgi reg insataller

dsmith

Thought one radiator had to not have a thermostatic valve in ?

What controls the boiler firing cycles - The Controller, Thermostat or the boiler itself ?

Deano

imlach

Hi, Thanks for all replies...

The radiators on ALL the radiators are currently set to 5.
However, when the plumber installed the rads, he worked out what size of rads we needed based on room size etc.

However, we have sanded floors, sash & case windows (single glazed), not fully installed the roof insulation yet, and no insulation in the cavities (it is a brick built cavity wall house) - and house is from 1930's - it is also detached so exposed to all prevailing winds etc - IE WE ARE DOING ALL THE
BAD THINGS!!

Reason for this is we bought the house as a dump, and still doing bits to it - but all that is left to do is the insulation really.

Worried that plumber based his calcs on a carpeted double glazed modern house - and maybe we are under-radiator'ed!!???!!

House does take a while to heat up on a cold night - never had a detached house before though, so this may be normal.

imlach

Also - someone suggested putting a thermostat valve on hall radiator - this would mean that the boiler would run continuously though - is the whole point of the wall stat such that it switches the boiler off and is therefore more economical???

If boiler is running continuously, does it use less gas - ie, if water in loop is at max temp, does the BOILER switch off the burners too???

If so, I could see that a wall stat could be removed..........