Any heating engineers on here.?

[IDM]

In our home we have an extension which has a separate (underfloor) heating system to the rest of the house.

A few days ago we tried to boot this up having had no demand for the previous 6 months or so.  However the heating pipes did not warm up in those rooms.

The boiler is working, the system pressure is good (no leaks), the thermostat valves aren’t stuck, the pump isn’t stuck and receives demand, and the pump and manifolds have been bled.

Today however I discovered that the valve (pictured) should open, controlled by the micro switch in the housing, when there is demand on the system.  However the lever under the housing didn’t move across in the “auto” setting which says to me the motor inside isn’t working, or the actuator or even the valve was sticking.  I then found that I could push the lever over and fix it in the “manual” position, and then the valve clearly opened and the flow meters showed the water was getting into the system now.  The rooms began to heat up.

But when I then put the valve control lever back into auto,  the return spring switched it off, even with a demand on the system, which shows to me that the micro switch motor is malfunctioning.

So, I have put the lever back to manual and left only one of the room circuits switched on.

Clearly I will need to get the micro switch actuator box changed, possibly the valve too, but it doesn’t seem to be an emergency..

My question is, will leaving this control lever in manual for a lengthy period cause any further problems.? 

[drfchound]

It shouldn’t cause problems IDM because the thermostat should shut the UFCH off when it is up to temperature.
I see that the valve is a Salus one.
Before I retired (almost three years ago now) Salus had a no quibble product exchange warranty.
It might be worth enquiring with whoever you got it from to see what that situation is.

[IDM]

Thanks - he boiler is due it’s annual service in a couple of weeks so I’ll check then - I was just worried it might be a more urgent problem..

[silent majority]

Salus?

Cheap Chinese rubbish I'm afraid.

Sorry IDM.


Interested to know how that system regulates the water temperature in the UFH section though.

[IDM]

It doesn’t.. The thermostat valves and the mixer unit do that..

It controls a valve which is either open or closed, to allow water to circulate to the UFH circuits.

In theory, when any of the (we have 3 circuits) wall mounted digital thermostats sends a demand, that initiates the heating selection in the boiler, opens the relevant thermostat valve in each circuit at the manifold, and turns on the pump.  It also should tell this control valve micro switch to open the valve.

However, as each circuit has its own digitally controlled thermostat valve, opening the circuit(s) as required, this extra control valve is redundant.  If none of the thermostats sends a demand, the boiler isn’t iring and the pump is off, the thermostat valves at the manifold stay shut and there is no flow anyway.

To top it all, the wire coming out of that box isn’t fixed at the other end in the electric control box at all - it is safe, it was never connected in the first place..

The plumber who dropped by today was quite flummoxed that the valve was put in place originally as it was never required.

What we think has happened is that on installation the valve control was set to manual so the valve itself was permanently open.  Then at some point since last winter we must have knocked something against the box - entirely feasible - which dislodged the lever from manual to automatic.  Then because there couldn’t be an electrical demand on the micro switch, it closed by default due to the return spring.

The plumber has removed the control box physically from the now open valve stem, so it is impossible for it to close itself.