camray 2 hw problem

[stephanh]

Morning all

Just moved in to this place and have inherited I have a camray 2 - fitted 1990 - which for past 2 weeks has been fine.
Boiler is now running the heating when I switch on for hot water. It has 2 switches, one for HW and one for heat. For HW it is just the one switch but for heating both have to been 'ON'
Have turned room stat to as low as possible, but boiler still heating when HW on.
I am loath to commit too much cash to the problem as I have plans for a new boiler in the new year, so is this a problem I can fix myself?

 

[ericmark]

I have found my oil boiler, is a collection of parts, and looking for instructions for the boiler there are many variations for what seems to be same boiler, so it is hard to know what you have.

My boiler runs on a C Plan, and there is no way to turn DHW heating off, in theroy I can have only DHW with no CH but not the reverse, I say in theroy as often thermo syphon can also cause CH radiators to heat, but since I have a flat and main house, I have two pumps, and two motorised valves, so I can turn CH fully off.

During the summer I use an immersion heater for DHW, works out far cheaper, but to control the DHW heating I would need a thermostat on the cylinder, and a motorised valve, I have neither, I talked to plumber about fitting a motorised valve, and he advised against it, saying the boiler has no run on, so heating the DHW is how the boiler cools down, so advised not to fit one.

What I did do was fit a Nest Gen 3 thermostat, hind sight not the best thermostat, but what it did do was allow me to program in for summer DHW heating in ½ hour slots, 4 days a week, which was how I heated DHW in summer, I had heard so many times how much cheaper oil is to electric I just assumed it was cheaper to use oil, the boiler would only run for around 20 minutes each time is switched on, and around 20 kW so that was around 25 kWh per week, however when solar fitted, also fitted a iboost+ (realised latter simple time switch would have been better) however it logs how much power used, and I use around 2.5 kWh per week, clearly down to loses in boiler and pipe work, so seems it would have been cheaper to use the immersion heater.

It also seems oil boilers are far better made to gas boilers, they also need more regular servicing, as the jets need replacing around every two years, and the pressures need re-setting every year, but they can easy last 25 years, and found moving from gas to oil, that oil cheaper to run, not a clue why, this house far larger than the last one, maybe it is simply no standing charge on oil?

 

[RandomGrinch]

Boiler is now running the heating when I switch on for hot water. It has 2 switches, one for HW and one for heat. For HW it is just the one switch but for heating both have to been 'ON'
Have turned room stat to as low as possible, but boiler still heating when HW on.

It sounds as if you have a 'Gravity' central heating system - when you turn the hot water on, hot water will naturally circulate around the coils in the hot water tank, by convection, heating the tank contents.
To operate the central heating, additionally, a pump is turned on to circulate hot water to the radiators.

Explainer here..

Gravity Hot Water

There are several modern smart stats that can handle gravity systems i.e. Hive has a gravity setting, but many would recommend upgrading the system to a fully pumped one, for better efficiency.

Could I clarify what the problem is though?
It sounds as if when you turn the Hot water on by itself, the radiators still get hot - does the pump remain running?

 

[stephanh]

Ahh, it may be that I have resolved the matter (at least for the mo') - I hit the 3 way with a hammer. Well, it was more of a tap, tap, really. Anyway, the valve seems to be behaving a little better. With a bit of luck it will survive until the new year. Got fingers crossed.

Thanks for your replies.