central heating not working - or is it just a setting

Please can someone help me tell if our CH is faulty or if i've just got the settings wrong? There are more knobs to fiddle with on than the CH in our previous house & I'm not sure what thay do or how they interact. Pictures at :

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CH works OK during day on timer, but seems to "go to sleep" at night (even when timer says ON and thermostat is calling) and won't get radiators warm. Also doesnt start warm in the morning. Plenty hot during day!

I've managed to "wake it up" last 2 nights by 1-Switching programmer on & off at mains or 2- turning up the knob on the water tank.

I can work the thermostat and timer (just like old house) but this one also has a big knob 0-5 on the gas heater (see pictures) which makes the gas flame appear & go higher sometimes, other times turning it up has no effect - no flame to be seen.

What is this knob supposed to do & what should I be doing with it & how does it interact with the knob on the water tank, which I think is the water temperature? (see pictures)

Have I got one of these knobs too high or something to cause the problem?

Thanks

Reply to
keith
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It sounds from what you say that the radiators only get hot when there is

*also* a demand for domestic hot water. Has it ever worked properly? If not, it has not been installed and/or wired correctly. From your photos, you have a Y-Plan system - fully pumped, with a mid-position 3-port valve to direct the water to the cylinder and/or radiators. [See
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and scroll down to Y-Plan]

This system requires the programmer to have a "HW Off" terminal in addition to "HW On" and "CH On" and it also requires the cylinder stat to have change-over contacts. If this is not done, the system won't work in CH-only mode.

If it *has* worked but has since stopped working, my money would be on a duff microswitch in the actuator on the 3-port valve. In the CH-only position (with HW turned off or satisfied) the system relies on this microswitch to turn the boiler and pump on.

Incidentally, the knob on the boiler only controls the temperature of the water produced by the boiler - unless you turn it right off - not whether it operates or not. Your problem is either in the wiring or in the actuator.

Reply to
Set Square

I'd guess that if you look (usually in the airing cupboard) you will find a motorised valve with three pipes into it and a metal or plastic box containing the drive motor attached to it. Possibly the motor has died at some time and someone has pushed the drive unit override lever across into the manual position which sets the valve to pass hot boilerwater to both cylinder and radiators. As the motor does not drive the valve all the way across the internal limit switch does not operate to call the pump and boiler into life. Turning up the water thermostat or running off some hot water thus calling for heat to the cylinder does ask the boiler and pump to operate and so you get heat to your rads. See the faqs for Y plan systems. Replacing the failed motor is a fairly trivial job and inexpensive Of course you could have an incorrectly wired system (g)

Reply to
John

........ Possibly the motor has died at

Thanks for replying, I've spotted there's yet another control which I think is the one you're refering to as it's on the valve. It slides from "Auto" at one end to "Mid" at the other. It looks like you can take a diversion on the way to Mid and go to an alternative position instead. There's a picture that calls this "Manual Override Only". The slider is set to "Auto" which I think you're saying is correct. (see valveswitch picture at

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Should it be set to one of the other settings?

Thanks

Reply to
keith

If its at auto then the chances are that the valve motor is ok if you are getting heating sometimes. However there is still a possibility that your motor has seized up with the valve open. Try switching off all power to the heating system and then going to the valve to assess if the lever is now "free" or requires pushing across against the spring to move the valve. Put the power back on and set the programmer and roomstat to heat required lightly touching against the lever and listening whilst doing this (you may need an assistant). If the valve is ok you should hear the motor and feel the lever follow the drive from hot water only to the heating position. If the valve is ok then the problem will require further tracing.

Reply to
John

When I moved in here I found a superb CH system, with the most amazingly crap wiring system imaginable.

The house was divided into three zones, so there are four 2-port valves. There is a hot water/CH timer. There are no thermostats anywhere in the house, not even on the tank.

When the hot water part of the timer is on, it fires up the pump and the hot water valve. When the CH part is on it goes through three switches on a very nice, custom made and labelled, switch panel to the three zone valves. The boiler is on all the time.

To keep things "tidy", the installer had carefully removed the multi-core cable from the valves and replaced it with 3 core, not using the microswitches at all.

I'm still speechless thinking about it.

We now have three room thermostats, each turning on the appropriate 3 port valve, as does the new tank stat. The four microswitches in the valves have been reinstated to activate the boiler. The pump overrun output from the boiler, which was previously u/c now runs the pump.

Reply to
Nick Atty

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