Heating works but no hot water

[daveleahy01]

I have an Ideal Icos HE15 Heat Only boiler which is about 2 years old.

Last week the hot water stopped working. The central heating ignites and works but when it comes to the hot water, the programmer says its on but there's not so much as a sound coming from the boiler.

On the Ideal website it says it can't be a boiler problem because the boiler can't differentiate between heating and hot water modes.

Luckily the system has a back up immersion which works perfectly which makes me think its not a problem with the storage tank either.

Has anyone any idea what the problem may be if it turns out not to be the programmer?

Thanks in advance.

 

[Agile]

Motorised valve or cylinder stat.

Tony

 

[daveleahy01]

Thanks for your reply Tony.

When I turn the heating or water on, the motorised valve becomes loose but is otherwise motorised when not in use if that helps. When i open the valve manually and use the heating to fire the boiler up this doesn't seem to heat the water up either as I thought it would. The gauges go up on the tank as it would if it was working but no hot water is coming out of the taps.

Should the motorised valve be motorised at all times?

 

[jackthom]

Untitled

• jackthom
• 19 Dec 2008
• 18

Is the valve a single 3-port one as above, or do you have a pair of 2-port valves?

 

[daveleahy01]

I have a pair of two port valves.

 

[jackthom]

Here's a diagram of the wiring which should be something similar to yours.

http://octaveblue.co.uk/c_heating/sp_hw.htm

If the hot water motorised valve is opening fully, as it should when the cylinder thermostat is calling for heat, the orange wire should go Live and fire up the boiler and pump.

If this isn't happening but the valve lever is becoming floppy, the valve has at least opened partly but it may be sticking before the internal microswitch has operated or the microswitch may be broken.


Manually opening the valve as wide as possible should activate the internal switch and fire up the boiler.

 

[Garfeild]

Thats a good diagram,innit?

 

[mcmarshon]

Check out the website !

 

[daveleahy01]

I got a plumber mate in who identified the valve which he thought it was. Today I changed the valve and its still not working.

If I switch the heating on to fire the boiler up and open the valve manually, then switch the hot water on it heats the water up but I don't want the heating on in this weather. If I switch the hot water on on its own the boiler is none respondant. I can only get the boiler to fire up through the heating.

 

[Hugh Jaleak]

If you feel competant enough with a multimeter then for starters I'd be checking you have power at the orange wire from the valve when HW is calling. I would think this is a wiring problem, the boiler appears to be ok, its just not getting the call to fire for HW.

 

[daveleahy01]

Right thanks lads, just an update.

I think I'll probably have to get someone in to sort it but I like the challenge.

The orange isn't going live when HW is calling and it won't fire up when HW is opened manually either.

I know its not the microswitch as the water heats up when the HW and CH are both calling just no HW on its own. As for the wiring it was ok for a year and a half and has never been tampered with apart from when I replaced the valve and I just went like for like.

Is it possible that the cylinder stat is not calling for any heat therefore not firing the boiler or would there have to be no HW at all for it to be the stat.

Cheers Dave

 

[mysteryman]

Check the cyl 'stat and programmer.

Opening the 2 port valve manually does not bring on the end switch because the motor does not go full travel in manual.

 

[Hugh Jaleak]

As mysteryman has said, check there is power to the stat from the programmer when in HW mode. If so, then check the stat is supplying the power to the valve when HW is calling before condemning the stat.

I would also check the grey to valve is live, it may be that whilst the stat etc is working ok, the HW valve is not recieving power to allow the boiler to fire. When in HW and CH mode the power is being supplied via the CH valve. Note that both grey wires supplying the power to the microswitches in both valves are connected to the same terminal, just might be a bad connection there...

 

[daveleahy01]

Having checked almost everything the grey to valve is live, the programmer seems ok and there is power to the stat when HW is calling.

In respect of the stat I'm not sure whether this is a normal fitting but the live goes into a thermal cut out first which is live when HW calls, from the cut out there's a connection to the stat but I can't get a live reading on the stat at all.

I've just rang the manufacturer helpline and he said it can't be a problem with the thermostat because I wouldn't be getting any HW at all if it was the problem. Is this right??

 

[Hugh Jaleak]

The grey to valve is a permanent live, so that should be live. Need to check you have 240v from stat on the brown to valve when stat is calling. If not then possibility stat is faulty.

Cant see what manufacturer is talking about! If stat is faulty its not telling valve to open and thus the boiler/pump wont run. Hence no HW!