Heating not working what to check?

drofluf

Boiler is OK a as I have hot water and heated towel rails in bathrooms but it won’t fire up for the heating timer. 

We’ve got TRVs on all radiators but they’ve not been touched, I’ve turned the room thermostat in the hall up to full and get a click at about 20 degrees. I’ve turned it on and off and cycled through the programs on the timer. 

Anything obvious I can try?

maharg101

Have you bled the rads ?

Edit: you did ask for obvious

Barney

drofluf said:

Boiler is OK a as I have hot water and heated towel rails in bathrooms but it won’t fire up for the heating timer. 

We’ve got TRVs on all radiators but they’ve not been touched, I’ve turned the room thermostat in the hall up to full and get a click at about 20 degrees. I’ve turned it on and off and cycled through the programs on the timer. 

Anything obvious I can try?

Check when you turn the stat on the light on the boiler goes on and off ....the heating light ...it will prove the stat is working 

monquixote

Sometimes that happens if the heating hasn't been on for a while and the valve has stuck. Giving it a tap with a hammer sometimes works (gently)

Johnnyseven

Has the heater timer broken or has it run out of batteries so can't talk to the boiler? We just bought a new (old) house and the heating and hot water work but the ancient timing clock is busted. The towel radiator was working as it's plumbed to the hot water rather than the central heating.

drofluf

maharg101 said:

Have you bled the rads ?

Edit: you did ask for obvious

no suggestion too obvious

Just checked the highest ones and they’re fine. Would need to move furniture to check the downstairs ones but as it was working fine earlier I don’t think it’s that.  But thanks for the thought. 

drofluf

monquixote said:

Sometimes that happens if the heating hasn't been on for a while and the valve has stuck. Giving it a tap with a hammer sometimes works (gently)

Thanks, heating was working recently but the valve was my first thought. But where is it likely to be? And I realise that’s an impossible question to ask online

drofluf

Johnnyseven said:

Has the heater timer broken or has it run out of batteries so can't talk to the boiler? We just bought a new (old) house and the heating and hot water work but the ancient timing clock is busted. The towel radiator was working as it's plumbed to the hot water rather than the central heating.

Timer is ok, I replaced it a few months ago following advice I got here. It’s also working for  the hot water - I can see the boiler fire up and it goes off if I turn off hot water whilst the boiler is “on” according to the timer

TTBZ

We've had this a few times and it's always been the diverter valve which gets stuck when it's not being used. Check your manual to find out which one it is then usually just giving the tap/screw a wiggle seems to do the trick.

Yorkie

TTBZ said:

We've had this a few times and it's always been the diverter valve which gets stuck when it's not being used. Check your manual to find out which one it is then usually just giving the tap/screw a wiggle seems to do the trick.

I was going to suggest this too. Ours has got stuck too this year. 

Jon

boogieman

So first obvious question : combi boiler or conventional system with a hot water tank? Second: are all the rads cold? If it’s the latter and it’s a conventional system, then it’s usually a fault on the three port valve.  (It’s in the feed pipework from the boiler and has usually got a square silver box on the top and wired up to the mains). It’ll have hot water from the boiler coming in through one leg, then it directs the water off to the radiators, the hot water tank, or both, depending on what the thermostats are calling for. 

So, turn the room thermostat up till it clicks on and then see if the pipework going to the rads out from the 3 port gets hot. Sometimes the valve sticks in place but what often happens is the synchronous motor inside (that moves the valve) packs up. It’s a fairly simple job to replace, just make sure you’ve turned off the power to the system. Screwfix sell one for £20 ish that fits most valves. Oh, almost forgot, you’ll need a torx bit to undo the motor screws.  

exocet

How old is your system? Hot Water + Bathroom Radiator was a common configuration in older "Gravity Fed" systems. If this applies to your system - the pump isn't working as its the pump that circulates hit water to the rads other than bathroom.

Hootsmon

...into a hotel

Johnnyseven

Is the boiler/water pressure at the correct level?

Dominic

boogieman said:

So first obvious question : combi boiler or conventional system with a hot water tank? Second: are all the rads cold? If it’s the latter and it’s a conventional system, then it’s usually a fault on the three port valve.  (It’s in the feed pipework from the boiler and has usually got a square silver box on the top and wired up to the mains). It’ll have hot water from the boiler coming in through one leg, then it directs the water off to the radiators, the hot water tank, or both, depending on what the thermostats are calling for. 

So, turn the room thermostat up till it clicks on and then see if the pipework going to the rads out from the 3 port gets hot. Sometimes the valve sticks in place but what often happens is the synchronous motor inside (that moves the valve) packs up. It’s a fairly simple job to replace, just make sure you’ve turned off the power to the system. Screwfix sell one for £20 ish that fits most valves. Oh, almost forgot, you’ll need a torx bit to undo the motor screws.  

exocet said:

How old is your system? Hot Water + Bathroom Radiator was a common configuration in older "Gravity Fed" systems. If this applies to your system - the pump isn't working as its the pump that circulates hit water to the rads other than bathroom.

Both spot on.......as Boogie says ;what type of system 
Check the zone valve(s) first if it's a conventional system ......they can stick but you can often push them over manually if you already have a cylinder of hot water.........check pipe to valve.......if no joy
as exocet says .......the central heating pump may have stuck while not in use (that where all the shit in the system sits and corrodes the impellors )
Boiler water pressure in a combi system or lack of will have cut the thermostatic cut-out off ages ago and you wouldn't have hot water so it's not that and it wont be an airlock either
pump or Zone valve failing that programmer failure but you can check with override

drofluf

Thanks, it’s a conventional boiler, I’ll see if I can locate the valve in the morning. 

wolsnah

Check the actuator itself as well that turns the hot water/central heating valve. In our old house ours used to fail about every five years and cost about £60 for a new one. It would have been taken apart and checked if it wasn't for the pressure being applied to get the house warm again.

exocet

drofluf said:

Thanks, it’s a conventional boiler, I’ll see if I can locate the valve in the morning. 

The valve (or valves - sometimes you have 2) is normally close to boiler, normally connected to the larger / fatter  pipes coming from boiler and will have "mains cable" style wiring.
The timer connects to the valves and the valves connect to the boiler via a junction box. 

The valve(s) normally have a silver metal cover where the wiring goes in. It's actually the valve that switches the boiler on - the timer drives the valve actuator - if it's working, it opens the valve and closes another set of switch contacts that causes boiler to fire. However, if the actuator (or solonoid) has failed (they do), the boiler won't fire up. As you have hot water, I'd say that you will have 2 valves (one for Hot Water and one for Radiators)....or...

If its an older gravity fed system, there are no powered valves. The timer fires the boiler which heats water. Hot water rises causing circulation in the heating coil contained in hot water tank that is normally located in the room directly above the boiler. It's common for a bathroom radiator to be included in same circuit. For heating, the timer fires the boiler AND turns the pump on to feed the radiators. 

With this sort of system, you can have Hot Water OR Heating and Hot Water. You can't have heating without Hot Water. Pump failures are very common because for 6 months of the year, the pump is sitting in sludgy water without turning because the heating is not used. Come winter, the pump has ceased up and radiators fail to warm up.

drofluf

Ok I took the cover off. Which is probably the limit of my technical ability

Not sure where I should be looking for the valves?

It’s a Worcester Greenstar ri. About 5 years old, can’t be more specific as it was fitted by the previous owners. 

There are two fat pipes that come out of the bottom and then loop behind to disappear upstairs. This would suggest 2 valves I think?

chillidoggy

2-way valve for the heating circuit goosed. Or rather the synchron motor that moves it. I’ve changed loads of these and the symptoms are as you describe. You should have an override lever on it so you can see if it’s working as well as latching it open.

exocet

Where do the pipes that emerge from the top of the boiler go? Find your hot water tank - I suspect you'll find the motorised valves there. You have a new system so it won't be gravity fed / there will be valves that are part of electrical circuit for starting the boiler. As Chillidoggy says above, the valves will have override levers that you will be able to move. If timer / room stat is calling for heat when you move the lever - it should cause boiler to fire up / pump to run.