No hot water, just heating

kat263

Hi, I was after some advice please. Just moved into a rental house with a conventional boiler (a Suprima HE). I set the timer control so the central heating is off and the hot water is on. However, after about 5 hours the hot water is still freezing cold and the heating has been on constantly...

The burner light on the boiler changes between being on constantly and flashing (about 1/2 minutes of each, alternating between the two). Not if this is what is meant to happen? I assumed it should be on constantly if it is heating water.

I have contacted the landlord who said that the hot water tank just needs time to fill up. I appreciate that but I am concerned about the central heating being on when according to the timer it is off (and vice versa with hot water)

Any advice on what it could be please. Research is suggesting diverter valve?

datostar

If it's a conventional system with loft tanks (cold water and ch expansion) and unvented hot water cylinder there will likely be a 3 port motorised valve somewhere in the system (possibly near the hot water cylinder). That's favourite for your problem. The valve itself can jam due to sludge or scale, or the valve head motor (in a metal box mounted on the valve body with cables going into it) can fail. It means that thermostats will have no effect and the system will continually call for heat from the boiler. Your intermittent boiler firing will then be due to the boiler itself reacting to the hot water returning to it. It sounds as if the motorised valve has stopped in the heating position with no flow to your hot water cylinder.

kat263

Thanks for this reply. It sounds like that could be a possibility. Is this something that a professional needs to sort out?

molerat

Something the landlord needs to sort out.

southcoastrgi

What happens if you reverse what you are doing on the timer ie heating on h/w off ?

[Deleted User]

Think yourself lucky, we have no hot water or heating!

datostar

southcoastrgi wrote: »

What happens if you reverse what you are doing on the timer ie heating on h/w off ?

Probably make no difference if the motorised valve is not operating.

Heedtheadvice

True, datostar, and a mid postion motorised valve seem a likely culprit....... but Southcoast is very experienced and puts forward a good test to help diagnose where the problem might lie. It is quite plausable that the valve set up is different (a two valve system), that the fault lies in the controls, it has been installed incorrectly, a thermostat has failed, the system needs bleeding or the OP has misunderstood the controls.


It is also true that the landlord is legally responsible for any repair required (and the locating of it!) rather than the tennent who should not attempt a repair. However a bit of understanding and diagnosis should help make the case for a repair.

After half an hour of demanded heating of water there should be a definite substantial increase in temperature that can be detected after only 10 minutes and if central heating is not demanded it should still be cold/cooler.

stator

Since you have a hot water tank, you should check if there is a switch for an immersion heater. You can use this to provide hot water until you figure out what is wrong with the boiler control and get it fixed.