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Central heating

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Our oil boiler is a gravity fed non combi system. Divertor valve has two pipes only and is wired directly into hall thermostat (i think this controlls if boiler heats hot water tank or radiators), it… Read More
lumsdot Avatar
2y, 7m agoPosted 2 years, 7 months ago
Our oil boiler is a gravity fed non combi system.
Divertor valve has two pipes only and is wired directly into hall thermostat (i think this controlls if boiler heats hot water tank or radiators), it is not electrically connected to boiler or hot water tank in any way.

Boiler timer box is in kitchen and is just a simple on off timer, if it is turned off boiler is off, so that is ok.

But if timer is on, i.e in evening and we have hall thermostat set to 20 , but hall temp is 22 then boiler keeps cycling On and off for no reason (tap water is very hot) boiler does have its own thermo stat but is turned down to a sensible place).

Would like boiler to turn off completly if hall thermo stat tells it to,. But this may mean in summer when hall thermostat is mostly off we woud get no hot water.

Was thinking could replace timer with a
https://www.plumbnation.co.uk/site/honeywell-cm927-wireless-7-day-programmable-room-thermostat/?gclid=CPSczuXNwcICFW3MtAodBTAACg

This would controll both timing and thermostat directly to boiler. could the divertor valve be disconnected and just left in one position would the hot water going through radiators still flow through the coils in hot water ank.

Longest post in history sorry
lumsdot Avatar
2y, 7m agoPosted 2 years, 7 months ago
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#1
Link to timer thermostat

Your text here
#2
Just noticed the wireless thermo above has six time/ temp settings a day. So in morning first temp could be set very low to make sure boiler came on to heat hot water.
Just not sure what the diverter valve is doing, i think it may just isolate the boiler hot water from the radiator circuit.
, i.e only really needed in summer when you want hot water but cold radiators
#3
What is the question?
I looked for a ? But couldn't find it ;)

Edited By: Oneday77 on Dec 12, 2014 23:25
#4
Oneday77
What is the question?
I looked for a ? But couldn't find it ;)

Problem is hall thermostat is not asking for heat, but boiler is still cycling on and off constantly heating hot water.
Think need to replace boiler timer with a combined timer/thermo stat, which should fix problem.
But what to do with hot water diverter valve, just disconnect from old thermostat?
#5
It sounds like your hot water tank has some form of thermostat that is linked to the boiler. I know you said it wasn't, how else would the boiler know to kick in?
If your thermostat in the hall is just a basic temperature dial, PM me your address and I'll stick a spare in the post. I bought about 4 from B&Q for 10p each as spares ;) yours could be faulty. Worth swapping out as a test.
#6
Is it a properly installed system ? Hall Thermostat which I presume is wireless should only control the Heating output of the boiler . The Hot water output of the boiler should be controlled by a thermostat in your Hot Water tank. When the thermostat is turned low then the HW side of the boiler should work with the HW tank to provide just Hot Water.
Though not a oil burner (mine was gas ) I had similar problems - it was the 3 Way valve (about 5 times in 8 years that failed ) , Basically if both Thermostats (tank & CH) are below their setting it moves to allow hot water from the boiler to Tank and CH . If only CH required it moves to allow hot water only to Rads and not the tank . It also moves to its third position if CH is warm enough (ie thermostat temp exceeded) but tank thermostat is below temp ,and pumps the boiler output through the HW tank .
Hope that makes some sort of sense -would be much easier with a diagram so best look it up - Central Heating, 3 Way valve . My point is mine failed regularly ,needed heating to be on to get hot water - or vice versa . Can sometimes be cured (for a while ) by knocking said valve with a small hammer or pliers to free it . You can spot said valve as its T shaped {the pipes ) with an electric box sat on top of it .
Look up 3 way valve and I hope my longest answer in history made some sense .:)
#7
lumsdot
Link to timer thermostat

Your text here
For that price, spend a little more and get a smart heating solution. You could try Tado for a year for about £60.
Danfoss, I think could be Honeywell do a system that allows you to make each radiator a zone but it gets pricy pretty quick.
#8
get a combi, we saved a fortune on gas over our old gravity system
banned#9
yes.
#10
Oneday77
It sounds like your hot water tank has some form of thermostat that is linked to the boiler. I know you said it wasn't, how else would the boiler know to kick in?
If your thermostat in the hall is just a basic temperature dial, PM me your address and I'll stick a spare in the post. I bought about 4 from B&Q for 10p each as spares ;) yours could be faulty. Worth swapping out as a test.

No thermostat in hot water tank, boiler just kicks in when told to by timer. Thermostat in hall is new and works ok thanks
#11
rogparki
Is it a properly installed system ? Hall Thermostat which I presume is wireless should only control the Heating output of the boiler . The Hot water output of the boiler should be controlled by a thermostat in your Hot Water tank. When the thermostat is turned low then the HW side of the boiler should work with the HW tank to provide just Hot Water.
Though not a oil burner (mine was gas ) I had similar problems - it was the 3 Way valve (about 5 times in 8 years that failed ) , Basically if both Thermostats (tank & CH) are below their setting it moves to allow hot water from the boiler to Tank and CH . If only CH required it moves to allow hot water only to Rads and not the tank . It also moves to its third position if CH is warm enough (ie thermostat temp exceeded) but tank thermostat is below temp ,and pumps the boiler output through the HW tank .
Hope that makes some sort of sense -would be much easier with a diagram so best look it up - Central Heating, 3 Way valve . My point is mine failed regularly ,needed heating to be on to get hot water - or vice versa . Can sometimes be cured (for a while ) by knocking said valve with a small hammer or pliers to free it . You can spot said valve as its T shaped {the pipes ) with an electric box sat on top of it .
Look up 3 way valve and I hope my longest answer in history made some sense .:)

Its an old system, with no hot water tank thermostat, it works but is wasteful in that it is only really goes off if timer tells it to go off. Think combined timer/ thermostat direct to boiler will fix it,
Our Diverter is two way, so think it can heat both rads and hot water tank or just hot water tank
#12
lumsdot
Oneday77
It sounds like your hot water tank has some form of thermostat that is linked to the boiler. I know you said it wasn't, how else would the boiler know to kick in?
If your thermostat in the hall is just a basic temperature dial, PM me your address and I'll stick a spare in the post. I bought about 4 from B&Q for 10p each as spares ;) yours could be faulty. Worth swapping out as a test.

No thermostat in hot water tank, boiler just kicks in when told to by timer. Thermostat in hall is new and works ok thanks
Trust me there will be a thermostat ,probably strapped to the outside of your HW tank (under the insulation ) . Otherwise you would have scalding HW all the time . Look for that 3 way valve - that's your problem -nothing to do with thermostats or timers - Honest :)


Edited By: rogparki on Dec 13, 2014 00:12
#13
lumsdot
rogparki
Is it a properly installed system ? Hall Thermostat which I presume is wireless should only control the Heating output of the boiler . The Hot water output of the boiler should be controlled by a thermostat in your Hot Water tank. When the thermostat is turned low then the HW side of the boiler should work with the HW tank to provide just Hot Water.
Though not a oil burner (mine was gas ) I had similar problems - it was the 3 Way valve (about 5 times in 8 years that failed ) , Basically if both Thermostats (tank & CH) are below their setting it moves to allow hot water from the boiler to Tank and CH . If only CH required it moves to allow hot water only to Rads and not the tank . It also moves to its third position if CH is warm enough (ie thermostat temp exceeded) but tank thermostat is below temp ,and pumps the boiler output through the HW tank .
Hope that makes some sort of sense -would be much easier with a diagram so best look it up - Central Heating, 3 Way valve . My point is mine failed regularly ,needed heating to be on to get hot water - or vice versa . Can sometimes be cured (for a while ) by knocking said valve with a small hammer or pliers to free it . You can spot said valve as its T shaped {the pipes ) with an electric box sat on top of it .
Look up 3 way valve and I hope my longest answer in history made some sense .:)

Its an old system, with no hot water tank thermostat, it works but is wasteful in that it is only really goes off if timer tells it to go off. Think combined timer/ thermostat direct to boiler will fix it,
Our Diverter is two way, so think it can heat both rads and hot water tank or just hot water tank
That really is an old system then ! As you say wasteful - we must be talking 60s /70s here ! But even with a 2 way valve it should still supply HW when the CH is turned off . Still think the problem is with the valve even if its an old 2 way -still worth giving it a few taps :)


Edited By: rogparki on Dec 13, 2014 00:42: spelling
#14
As said before, there is likely to be two, two way diverter valves.

These valves use a syncron motor, which will drive the valve open and when it reaches this point, switches in the valve head switch the boiler on.

What usually happens is that the motor clutch slips so the valve never opens fully and the switch never commands the boiler correctly.

New motor like this

http://www.ebay.co.uk/itm/SYNCHRON-MOTOR-UNIVERSAL-SYNCHRONOUS-MOTORISED-VALVE-/250694123761?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item3a5e88c0f1

Can fix the problem and doesn't need the system to be drained, unlike if you change the whole valve unit. Make sure that the mains power supply is switched off before changing the motor - risk of electric shock!
#15
If it's gravity HW like you said and being an old system you will have a Silver metal box somewhere attached to the pipework for your heating ( only 1) and you need to have the pipework cold ( leave off for a few hours). Once cold then turn on the HW only, leave the thermostat for the heating off. and check to see if the rads heat up. If they do then your 2 port valve will be passing and needs to be replaced - this valve could be under the floor or in a cupboard, could be anywhere. That would be why your rads are still on even though the thermostat isn't calling for heat
#16
mjccam
If it's gravity HW like you said and being an old system you will have a Silver metal box somewhere attached to the pipework for your heating ( only 1) and you need to have the pipework cold ( leave off for a few hours). Once cold then turn on the HW only, leave the thermostat for the heating off. and check to see if the rads heat up. If they do then your 2 port valve will be passing and needs to be replaced - this valve could be under the floor or in a cupboard, could be anywhere. That would be why your rads are still on even though the thermostat isn't calling for heat

Yes have a silver box which is a 2 port divertor, system is working as designed, but is a rubbish design. Thermostat in hall is connected to diverter, once upto temp the diverter is activated and stops flow of water to radiators, but not hot water tank, boiler fires up every now and again to keep heating hot water circuit ( which is wastefull) .
Think my plan is to leave existing thermostat on diverter. But put another thermostat in series with the output of the timer, this really would turn boiler off once house is warm.
Would set old thermostat so that diverter is always off and both rads and tank get flow of water. Obviously in summer would need to change old thermo stat temp so that we get hot water only
#17
You should look into grants for new boiler.Any outlay should be recovered in a short time with fuel savings. 8)
#18
lumsdot
mjccam
If it's gravity HW like you said and being an old system you will have a Silver metal box somewhere attached to the pipework for your heating ( only 1) and you need to have the pipework cold ( leave off for a few hours). Once cold then turn on the HW only, leave the thermostat for the heating off. and check to see if the rads heat up. If they do then your 2 port valve will be passing and needs to be replaced - this valve could be under the floor or in a cupboard, could be anywhere. That would be why your rads are still on even though the thermostat isn't calling for heat

Yes have a silver box which is a 2 port divertor, system is working as designed, but is a rubbish design. Thermostat in hall is connected to diverter, once upto temp the diverter is activated and stops flow of water to radiators, but not hot water tank, boiler fires up every now and again to keep heating hot water circuit ( which is wastefull) .
Think my plan is to leave existing thermostat on diverter. But put another thermostat in series with the output of the timer, this really would turn boiler off once house is warm.
Would set old thermostat so that diverter is always off and both rads and tank get flow of water. Obviously in summer would need to change old thermo stat temp so that we get hot water only

What you really need is to convert your system to "fully pumped" - add another diverter valve on the HW so everything is controllable individually.

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