Central Heating advice needed

[christopher]

Central Heating Problems/Woes

My hot water/central heating does not appear to be running correctly , hot water is cold in the morning and several rads fail to get hot . It has worked OK in the past

My boiler is in the garage and the hot water cylinder and pump and other stuff are in the airing cupboard

The pump appears to have a rotory flow control switch but it has the odd dead spot .

Apart from the Groundfos pump there is a tank stat connected to a Honeywell 42002116-0011 box which in turn is connected to a Honeywell 8903 and ACL Drayton 2 port valve in the hot water primary..

There is also a Myson Aerjec 11 unit in one of the pipes which is in the pump circuit

The 8903 has a switch between auto and manual and is set to auto

The boiler controller is in the garage and the boiler is an Ideal Mexico 2

The controller is a modern Honeywell unit .

The pipework runs are not all visable

The system was installed when the house was built about 30 years ago

Can the boiler heat HOT Water and run the central heating at the same time ?

If I could understand how its supposed to work I might spot the problem

Thanks

Chris

[John]

If some rads are hot and some are cold then you first need to check that the radiators are tuned on and balanced and bled.

I am not familiar with the components of your system - usually there is a diverter valve that gives priority to Hot Water - when that is satisfied the valve spring returns to the C/H position to heat the radiators. I presume there is a thermostat strapped to the cylinder. If so - this operates the diverter valve.

[John]

Sorry - just read again and see that you have a cylinder stat.

Does the two port valve actually move?

[newshound]

Do you have thermostatic radiator valves? One fairly common fault is where the pins stick down if they have been wound fully closed. The first thing is to remove the "control" bit; this will expose a pin which you should be able to push in against a spring, and it springs out again. You won't be able to do it directly with fingers, you will need to use a hard object. If it springs in and out, it is OK. If it doesn't move, tap the pin on the top with a small hammer (as if you were nailing in a tack) and it may free up.

Another common fault is a seized pump; remove the big chrome screw from the centre, this exposes the rotating spindle which has a screwdriver slot in it. If it doesn't rotate freely, try exercising it back and forwards and it may free up (some water may come out).

Probably worth reading the wiki

[newshound]

and remember that you won't necessarily *see* the manual lever outside move when the electrics go on and off (this just confused me on my new Honeywell diverter). On mine, with the power on, the lever moves very freely. With the power off, when you move it you are operating the valve against the spring, so much more force is needed; when you let it go it returns slowly because the return is "governed" by the gearbox. So although you can't directly "see" the valve moving, you can tell if it is without dismantling anything. If you have a broken motor or gearbox you won't get the "free" movement. Incidentally motors and gearboxes can often be replaced relatively cheaply without disturbing the "wet" side.

Does this make sense?

[TheScullster]

wrote

Is the system vented with a header tank? If so, is the tank ball float functioning correctly? These can stick shut and let the tank run dry - eventually the water on the hot side evaporates leaving nothing to circulate round the rads and hot water circuit.

Phil

[christopher]

On Wed, 17 Nov 2010 16:12:15 -0000, "TheScullster"

Well lads thats given me plenty to think about , I will report back with a nother installment

wrote:

[Spamlet]

likely if the CH has only just come on since last year.) it is safer to tap the central spindle via a wooden drift, with the motor turned on: then it will pop back and begin rotating. The spindles are very brittle and I have broken a perfectly good one in the past by trying to turn it with a screwdriver.

Other than this and the rad pins you have noted, the most common fault we hear of in these columns is the diverter valve, and it is usually the switches in the actuator heads that fail, rather than the valves themselves.

S