Central Heating Problem

bride2be2012

Hi, hoping some can help me, I don't know much about boilers so please be gentle with me!

We are in a rented house, and our combi boiler seems to be a bit tempermental. I've never had a house with one of these before, so don't know if it's working right or not!

We have the boiler in the kitchen, a thermostat in the living room and radiators have individual controls too. Sometimes when the timer on the thermostat kicks in, the boiler fires up but only runs for a minute or two then cuts off. The thermostat shows it is still calling for heat though. It then takes the boiler maybe 15/20 mins to start up again. As a result, it takes forever to get the house to heat up. The other thing we have noticed is that if the heating is on, then run the hot water, the boiler switches the heating off when we turn the tap off.

The boiler is a Halstead. The fault light never comes on, so we are unsure if there IS a fault or not?

keystone

It sounds as though the TRVs may be shutting down before the room reaches the the temperature called for by the roomstat. Open the TRVs up to max and see what happens.

DHW always has priority over heating on a combi. They are designed that way.

Cheers

macman

Correct. While the hot tap is running, all the flow goes to the DHW circuit, and none to the CH circuit.

jennifernil

But the OP states the CH goes completely OFF when they stop running HW.

This is not right.

keystone

You are correct OP does indeed say that and I must confess that I read it as "on" which is normal. Perhaps OP would confirm if they mean on or off?

Cheers.

bride2be2012

sorry, what are TVR's?

The CH goes off when we turn the HW on, and stays off once we turn off the HW, maybe for a good 20 mins or so, then eventually the CH comes back on.

Myser

I initially thought the TRV's (Thermostatic Radiator Valves) but then re-read the post.

If they were experiencing a pulsing effect i.e. TRV's cut off HW flow to radiators rather than them reaching full temperature -> thermostat detecting drop in temperature and sending a call for heat to the boiler, opening all the TRV's fully would solve this pulsing.

However, the OP said the thermostat shows that it is calling for heat yet the boiler is off?

Myser

A TRV looks like this:

bride2be2012

yes, thermostat shows it's calling for heat, but the boiler remains off. It's almost as if there is a time delay - time on thermostat kicks in, boiler fires up, stops after about 2 mins, then starts up again about 15 minutes later. It then stops/starts/stops/starts etc, either until the timer goes off again, or very occasionally it will stay on long enough for the room temp to reach the thermostat setting. When it does it's stop/start routine, the thermostat is almost always showing it's calling for heat.

Myser

What is the make and model of the system timer?

Have you tried resetting it to factory settings?
(Note, you will lose all your programme settings!)

keystone

bride2be2012 wrote: »

sorry, what are TVR's?

These:



:D. Sorry - t'was flippant - ignore that whilst I get me coat then.

The CH goes off when we turn the HW on,

which is what it is supposed to do.

and stays off once we turn off the HW, maybe for a good 20 mins or so, then eventually the CH comes back on.

I've still got a feeling in me water that its the overheat stat keeping it all off until its cooled down enough to kick back in again. Open up all the TRVs as suggested before (remoce the heads even and see what happens. If that doesn't fix it them I'm wrong with this idea and we can look for something else.

Cheers