Help with my oil heating/water set up

Nat1977

Hi,

Just moved house and I cant seem to work out my heating/water timer controls, thermostats etc. Could anyone help?

Its oil fired, each radiator has a thermostatic valve.

The oil boiler is in an outhouse with a dial thermostat which is connected to a box with 'terrier' on it. there is also an on off flick switch connected to the 'terrier' box.



Then there is also a seimens digital controller indoors with on and off times and temperatures etc.

If I turn the thermostat down on the boiler, then nothing seems to come on at all, no matter what the settings are in the house. However, Once I turn the thermostat up on the boiler, it comes on, but then stays on giving hot water and heating. It's like the thermostst in the house is doing nothing?

I have the control in the house set to 18 degrees coming on twice a day.

Cardew

In a conventional CH system the dial(thermostat) on the boiler simply controls the maximum temperature of the water that the boiler will produce.


For a test set the boiler thermostat to maximum.(which normally corresponds to around 80C*) with the CH off. It should then heat the Hot water tank to the temperature set on the tank thermostat whilst the digital controller is set to water heating on. When that temperature is reached the boiler will stop firing.


With Hot Water off and CH on and at least one TRV at maximum, the room thermostat will switch on the pump when the room temperature is below that set on the room thermostat. When the room temperature is reached(or the water temperature is reached) the boiler should switch off.


* water at 80C is very hot etc and radiators at that temperature could scald kids etc.

Nat1977

Thanks, but the thermostat that's in the outbuilding attached to the boiler is in addition to the water thermostat thats on the actual boiler. Its one of there: http://www.plumbnation.co.uk/site/honeywell-dial-setting-room-thermostat-t6360b1028/ and seems to correspond to the temperature in the room at the time. ie when it was hot out, I had to turn the dial right up to get the boiler to fire up.

Cardew

I cannot see any point in having a thermostat, as you show in the link, in an outbuilding.


However it would be normal to have a similar type of thermostat as a 'froststat'.


http://www.plumbase.com/tprod75098/section1821/hwell-frost-stat-3-22c-t4360a1009.html


The purpose of that device would be to switch on the boiler if the outbuilding temperature got low enough that there was a risk of frost damage to the boiler. However the setting on that would be typically 2C to 4C.


Could that have been wired incorrectly?

G_M

Not sure what the 'terrier' stat is, though I do wonder if it could be freeze prevention as it's in an outhouse.

If so
* set boiler stat high (start at max, try for day or two, reduce gradually as required) to ensure when the boiler fires up the water coming out is piping hot.

* set 'terrier' stat very low, so if temp in outhouse drops below freezing in winter, boiler will fire up

* set controls indoors so that at the times you want heat the boiler will fire up if the temp indoors drops below whatever you've set the indor stat for

* set individual radiator stats at required settings eg so even if the heating is on and the living room is being heated, bedroom rads go off (assuming you want bedrooms cooler than living room)

Then reduce temp on boiler stat untill you reach a point where the rads don't get hot enough because the water coming out of the boiler is warm not hot.

(of course, if I'm wrong about the terrier.....)

Cardew

If it is a correctly wired froststat it will have no effect on the CH/HW operation if the temperature in the outbuilding is above 2C to 4C(typically). It is only below that temperature it has any function; and will switch on the boiler regardless of the house digital controller. i.e. it has no function until we experience freezing conditions.


The OP states he must turn up the stat before CH works