Heating/ timer problem

[ptarka]

Hi guys,

I have 2 problems with my central heating and wondered if anyone can help please?
I have an oil fired boiler with FE setup.

1: When ONLY the hot water is on, the radiators get quite warm. Im assuming the 3 port valve isnt completly closing off the heating side. Does this mean the valve body is a bit gunged up and can be cleaned or is it a fault with the valve head?

2: I just put the heating on for the first time since last winter. Everything on the timer says the heating is on (Channel plus XL model 27) but the pump is not running and the boiler is not firing. As the hot water works I am assuming it is the CH part of the timer at fault?

Many thanks in advance guys..

 

[doitall]

Posting some makes and models would be a good plan

 

[MANDATE]

If the timer was at fault and the room stat did not work you would not have any form of heating, because valve could not move to mid position.
Knowing how the 3 port valve works would be valuable.
My opinion is that maybe the valve does not move beyond mid position, in which case it cannot trigger the micro switch that provides power out through the orange wire to light the boiler.
On the other hand it may move the valve to the correct position, but a faulty micro switch (dirty/burnt contacts) would prevent power out to light boiler.
If you check voltage on white wire it will test both room stat and programmer

 

[ptarka]

Thanks for your reply.

My system doents have a room stat, just TRV's. When you say a faulty micro switch (dirty/burnt contacts), do you mean within the 3 port valve head?
Also, will the pump not run unitl the valve has completed its operation?

I moved the lever on the valve (honeywell) from auto to manual. I could feel the valve move. Then i turned the heating on with the timer but still nothing.

 

[doitall]

Posting some makes and models would be a good plan

 

[ptarka]

Posting some makes and models would be a good plan

HORSTMANN H27 CHANNEL PLUS XL PROGRAMMER
HONEYWELL F5 9918 3 port valve
Wall star oil fired boiler
No room stat, just TRV's
Feed expansion setup

Hope that helps

 

[MANDATE]

Yes! the valve head has two micro switches each have two sets of contacts so that's 4 functions
(a) allows power from white wire to drive motor. or
(b) cuts off contact above and makes contact with grey wire so motor can be driven forward from mid position to CH position.

(c) allows power to PCB to produce and provide modified voltage to hold valve in mid position against the strength of the return spring.
(d) cuts off (c) when no longer required and allows power out of the valves orange wire.
So dirty/burnt contacts may not 'make' or 'break'

The boiler/pump cannot run in CH mode only without power from the orange wire.
Of course if HW is selected and not satisfied, the boiler/pump will run, because the power is supplied through the cylinder stat and not the valves orange wire.
The lever is provided to move the valve to mid position for draining down/filling.
So using the lever will not take the valve the full distance and not far enough to trigger micro switch to cut (c) and make (d)

I don't know how your valve is being controlled if you have no room stat. The white wire on the valve is being supplied from some source, otherwise the valve would stay put at HW only.

 

[Hugh Jaleak]

MANDATE, it can work (ish!). The 'Outlaws' (former inlaws!) have a 'S' plan system with no roomstat, they're looking at putting one in. I'm assuming that system is wired so the 'CH on' from programmer is wired directly to the brown on the CH valve. Clock puts heating on, valve is energised to open, thus powering pump/boiler as normal. (It just stays on until clock switches CH off again....)

I would presume the OP's system is similar, i.e. when heating is timed to come on the power is constantly applied to the valve until CH is timed to go off again. Roomstat is basically a switch to turn power on/off as room temp dictates. Not a very efficient way of doing things, if it's anything like the Outlaws place it can get very warm. (If the ex MiL gets too hot she opens the back door..... )

 

[ptarka]

Hi huys, been a little while but i finally found time to have a fiddle!

My goal was to find which wire was the CH on from the timer. After working out which one it is i put my tester on it and turned on the heating. Tester was reading nothing so I assumed the timer is at fault. I had already removed and inspecte the 3 port valve head which appears to be mechanically sound so in my frustration i turned the heating on again and gave the timer a sharp tap and bingo! valve moved, pump started and boiler fired up!!!!l

So, the problem is a loose connection in the timer on the CH on terminal.
The trouble is i cant get into the bloody timer. Does anyone know how to take one of these apart?? (HORSTMANN H27 CHANNEL PLUS XL PROGRAMMER)

The other problem is that the rads get warm in HW only mode and vice versa. Although the spindle on the valve felt nice and free is it possible it just has a build up of crap in there or is the head not turning the valve far enough?

Thanks in advance

 

[JohnD]

the rubber ball in the motorised valve perishes and wears out with age. If you take the motorised head off you can turn the spindle by hand, and you can also observe if the motor is working correctly.

If you think it is the programmer at fault, and all the visible connections are tight, consider getting a new one. There is a faint chance that if you take it apart and re-solder the PCB you might correct a dry joint.

btw unless you like burning £5-notes, you should get a room stat. You could even get a programmable stat so you don't need to rely on the programmer to time the heating.

 

[ptarka]

Thanks John,

A room stat is definately on the shopping list but I need to get the system working well first.

The first job is to get the timer apart to check the connecteions. If they are sound, then i need to look for dry joints on the PCB.

Question is, is anyone familiar with this timer? There are no visible screws or slots to insert a screwdriver. I dont want to force and break it but need to get it apart.

 

[ptarka]

Anybody please??

 

[JohnD]

consider getting a new one.

 

[doitall]

consider getting a new one.

And a room stat so it complies with the regs.

How anyone can run an oil boiler with no interlock is daft as a brush or loaded and don't care.

 

[ptarka]

consider getting a new one.

And a room stat so it complies with the regs.

How anyone can run an oil boiler with no interlock is daft as a brush or loaded and don't care.

I am neither. I only just recently moved in, hence the want to sort the heating system! I have also said above that I am getting one.

Also to consider getting a new timer without even looking inside this one first could well be throwing money away. Besides, I would still need to get this one apart to disconnect it.

Does anyone here actually have any sensible advice on dismantling this timer please?