3 big heating issues!

Can you post an audio clip of the pump noise - say on YouTube? That should help us.

And show us the timer and room stat you have too.

 

pump sounds goosed to me, i would just change it. Your other problems may not be to do with the stat or timer. do you have any motorized valves in the airing cupboard, pics!.

 

Hi Brez.

Yep, I can only suggest that's a knackered pump - failed bearings. Doesn't sound like air to me - that would be more 'whooshing' and 'gurgling'...

Gravity hot water? In which case the pump shouldn't come on with chust this.

The heating remaining on issue can only -I think - be down to a faulty timer. The room stat shouldn't be getting any power unless the timer is 'on' and sending power to it. The room stat then sends that power to the boiler & pump when it calls for heat.

The stat simply shouldn't be getting power if the timer is properly off, so best guess is that the contacts inside the timer are fused together and permanently on.

That's assuming you don't have any motorised valves? If you do, then these can cause the boiler to come on if they are faulty too, regardless of what the timer says.

 

Ah! These motorised valves are the most likely cause of pumps and boilers firing when they shouldn't - they have microswitches inside them that can stick.

Ok, question - how many pipes go to that motorised valve? 2 or 3?

(Any chance of side-on photo?)

 

Hi
Are you sure that you have a gravity hot water system?
Having a motorised valve suggests that you have a fully pumped system. Also the motorised valve, from your photo, appears to be a 3 port valve, ie incoming hot water from your boiler is diverted (or shared) to either the domestic hot water or the heating (radiator) circuit. The pump would then need to run to whenever either heating or hot water is required.
Also when replacing the pump, ensure all trapped air is bled from the pump (and all pipework) otherwise early failure of the pump is likely. Install the replacement pump in the correct orientation as directed by the installation instructions.

 

By the looks of it you dont have gravity hot water, its fully pumped ie 3 port valve.so u may have a goosed 3 port as well.

 

Hi Brez.

You've fed us a red herring...

As said above, you almost certainly have a fully-pumped system (which is good news).

That valve appears to have two 28mm pipes and one 22mm pipe going to it? 28mm pipes suggest an older system that's been upgraded by the addition of this valve, so I guess at some point your system was 'gravity'.

The central pipe on that valve should be coming from the pump and boiler. The outlet marked A should be going to the radiators and B to the hot cylinder.

The basic principle is that when the timer switches the CH 'on', it sends a signal (a 240V one) to the room 'stat. If the room stat says "the room is cold - I want heat", it then sends that signal on to the motorised valve. The valve moves to the A position and triggers a wee microswitch to turn on the pump and boiler.

Similarly with the hot water - if the timer says DHC 'On', it sends a signal to the cylinder stat and if that says "I'm colder than 65oC" (or whatever it's set to) it then sends a signla to the valve which moves it to the B position etc.

If BOTH sides call for heat, then the motorised valve goes to a central position - and stays there until one or t'other is happy.

You say in your first post that you have three issues with your system, 1, 2 and 3.

Almost certainly '1' is a faulty pump. '2' and '3' are very likely down to a faulty 3-port valve.

You will almost certainly have a bill of £200. And that's if you can replace them yourself

(Which is well within a competent DIYer's remit.)

If you are certain that's what's wrong...

 

Hi, To replace your 3 port valve, you will need to drain down your system to a level below the said valve. If the valve is upstairs, then just drain down the upstairs only.
I believe that all the major brand valves are of the same size, and you could replace it with a Drayton valve, rather than the more expensive Honeywell valve. (However if might be easier to replace it with the identical model). Check the pipe sizes first are they 22mm or 28mm ? A label on the valve might give details.

 

Hi again, Just enlarged your image, your valve has 22mm stamped on the nuts.

 

Hi Brez.

That's the cold water supply to the hot cylinder you are referring to - now't to do with whether it's gravity or no.

What your system is called is "vented", which means that the water in the system (boiler, rads and cylinder coil) is 'vented' to the air via the small expansion tank in the loft.

But, you are 'fully pumped' and not gravity.

As TD says, you do need to drain your system to replace that valve, but that doesn't have to be as scary as you think - well within the remit of a competent DIYer. The trickiest part will likely be swapping the wires - make sure it's power OFF and very carefully record where each wire goes...

Best thing to do is to surf the 'net for guidance - I bet there's lots of vids on PooTube. It would take some doing to explain it all in words, and I hate typing...

I'd double-check these pipe sizes, tho' - check what I said in post #12 above.

If the larger pipes are 28mm, then you must buy this size valve (the 22mm pipe to the cylinder looks as tho' it has a reducer on it as it goes in to the valve body.)

 

Blimey - I can't see that.

Doesn't make sense, does it? The B pipe is definitely smaller, isn't it? And it can't be 15mm, surely?!

 

There appears to be a small bump on the top of the valve (opposite end to the word Honeywell). If so, there shouldn't be any need to change the whole valve, just the actuator -the metal box part - which contains the motor and switches etc.

However, before rushing out to buy a new valve/actuator you should check that the timer is not at faulty. You say 'when the timer is off etc'. Do you mean it is timed to be off or actually set to Off (most timers show: Off, Once, Timed, On)? There is a difference as timed settings use a relay to switch over and the relay terminals can get stuck together. The Off position does not use the relay.

 

I have to say it's a bit strange if the heating only comes incorrectly on when the room stat says "I'm cold". If the room stat is having some control over this behaviour, then it suggests that it must be getting a signal from the timer even tho' the timer is orf.

However, the whole control system is actually surprisingly complex - that motorised valve does some strange stuff, you know... It has diodes and resistors inside to hold it at the central position for instance, using a weird kind of 'half-power' to do so. Then there's the microswitches which can behave strangely - either sticking on or sticking orf.

A few things we can be pretty certain off - the room stat will not work - have an effect - unless it's getting a signal from the timer. Ie - the room stat does not have its own power source, so cannot turn on the boiler unless it's first getting a supply from the timer. Of course, it's possible for the timer to be faulty and to provide a supply to the room stat when it shouldn't.

The motorised valve, however, does have it's own power supply going to it (to the microswitch that then turns on the boiler). So, if you were to manually move the valve to, say, CH position even with the timer and room stat completely 'off', then the boiler would still come on because you will have triggered the microswitch inside the valve.

I still suspect the valve, therefore, 'cos it's a funny beast and most likely to present funny behaviour. (It could be that the valve is actually being switched on by the DHW side of the timer, but it heats up your rads because the valve inside is 'letting by'...)

All guesswork, tho'.

Ok, a test. See your timer? It has green lights to indicate when it's 'ON'. Ok, try turning the timer on and off by using, say, the 'advance' button. Do this for the CH and the DHW in every combination - chust one, then t'other, then both, then none, then one on an off and on, then t'other... Press press press... Each time, listen for a solid 'click' from inside the timer, and look for the green light to come on/go off crisply and reliably at the same time as the clicks.

If the clicks and the green lights work crisply, then I think you can be confident that the timer contacts are good inside.

Ok, next test - the next time the boiler comes on heating when it shouldn't, check that CH green light and see if it's on or orf.

If the green light is off and the rads are still heating, my money is even more on it being the valve.

But - that's only a slightly-educated guess.