Underfloor heating issue - Hot Water Light off, system not heating

[MasterMark]

(It had to happen when it's cold outside....)

So I've had an UFH heating for 7 years, all been fine. But last night, I noticed that the rooms were chilly and no heat coming through the floor. The thermostats were on, the signals (from all 4 zones) were being sent to the wiring centre ok. I had hot water coming through the taps.

Checked the boiler, and the pressure was very low, so I re-pressurised. Pressure is still fine this morning.

I checked the UFH wiring centre, and the lights are on, but noticed that one light does NOT come on - the one for Hot Water (HW in the photo below).

1) Could it be an electrical/wiring issue with the wiring centre?
2) Could it be a pump issue?
3) With the boiler having lost pressure, I don't know whether that would cause a lack of water/pressure in the UFH system, and so I would need to refill it?

Any help or suggestions would be much appreciated! I tried calling the Heatmiser helpline, but after 10 minutes on hold i was still #14 in the queue.....

 

[cross thread]

Is the underfloor pump running ,is the underfloor zone valve opening

 

[Stuckinarut]

I'm guessing it's not a combi boiler?

 

[MasterMark]

I'm guessing it's not a combi boiler?

Nope, it's a system boiler (Worcester Bosch Greenstar).

 

[Stuckinarut]

Nope, it's a system boiler (Worcester Bosch Greenstar).

As above then, check the motorised valve

 

[MasterMark]

Is the underfloor pump running ,is the underfloor zone valve opening

There's a grundfos pump - should there be a noticeable sound coming from it? When I turn on a zone (and I hear the "click" and the light come on in the wiring centre), I can't seem to hear anything at all from the pump. The flow meters are pretty dirty/cloudy as well which probably isn't a good sign either

 

[Rodders53]

In the pics only one UFH Zone is calling Z1, two UFH thermo-actuators are lit (energised 2 &3 from left), NONE of the flow meters appear to show any flow ... (it does take some time, a few minutes, for actuators to open and allow flow, though).

That suggests no UFH pump working which could/should be fed from the UH4 output? Multimeter may confirm power to the pump? With power off check the pump impeller spins freely by removing the silver air bleed cap and a screwdriver (flat blade)? When powered they get warm to touch on the motor part of the casing (not water pipes) and can get quite hot, especially if 'stalled' for a long time. One can usually hear a little noise and they vibrate a touch - so feel it.

Boiler o/p probably operated the UFH motorised valve to operate the boiler via an UFH zone valve... The motors and/or the end microswitches can fail. Manual opening lever will be 'floppy' if motor opens the valve.

HW controller on the UH4 may not be used? If there is a separate timer for HW (and maybe rads) to control their respective motorised zone valves? Even if used there will be a time-clock input to the UH4 to make the HW relay and lamp work, so that timer needs to be calling for HW.

Water in some flow meters is very mucky, but not all, which seems odd; but likely a summer job unless a big drain down and refill is needed sooner.

 

[MasterMark]

you guys are all VERY good! Thank you! It was indeed the motorised valve - the little lever is sticking and won't activate automatically, which is why there was no activity from the pump/HW light. If I manually push the lever, everything kicks in and is working as normal. Looks to be a standard Danfoss part for about £40, and I'm assuming a straight plug and play replacement with no need to drain the system or anything drastic like that?

Re the flow meters, I'll follow your advice and leave until it's warmer to do a full drain and refill, maybe replacing the flow meters in the process just so I know everything is clean and tip-top.

 

[cross thread]

You can buy just the head, it’s normally a stiff spindle it operates that burns them out.

 

[MasterMark]

Cool, thanks. Just this bit then? It's a Danfoss Type HPA2

 

[cross thread]

Yes , oil the spindle as well

 

[MasterMark]

So the plot thickens. I have 4 zones (with 6 flow meters - for 2 of the zones, there are 2 flow meters associated with them because they each cover 2 rooms).

I turned the 4 zones on via their thermostats, one-by-one. 3 (or maybe even 4, too dirty to see) of the flow meters do not move when the thermostats are turned on, and the floors remain cold. So something not working. I wanted to try and take them off to clean to see if it made a difference, and have followed some youtube videos, but just wanted to be sure of the process and the parts of my manifold (which looks a little different to the ones online).

Diagram attached.

1. Turn off all thermostats, let system cool.
2. Close the red inlet isolation valve and the blue return isolation valve. I understand I now need to de-pressurise, but unsure of the steps to proceed before removing and cleaning the flow meters.
3. Note A - are they just 2 little escape valves that I would turn to let any air out (like bleeding a radiator), so nothing I need to do with them now?
4. Note B - not sure what the functions of these 2 valves is? Is it to shut off the openings of Note C?
5. Note C - would unscrewing these be done to drain the system? To refill system would I need to pump water through a hose into the top one, draining water into another hose/bucket of the bottom one? But in this case to depressurise, just open up the top one to let water out, before then removing and cleaning the flow meters?

Any additional info would be appreciated!

 

[Rodders53]

You need to find the install and operating instructions for your particular manifold, actuators and meters.
https://prowarm.com/pages/manuals may have them (or be able to identify what you have installed (as your flow meters look different to their current model), and may be another make altogether?
Even the latest manuals may be helpful in you understanding how the manifold works?

The Flow meters on manifolds can usually be adjusted by rotating a knob (may need a 'locking' ring released) and that can stop all flow and open up to a max... The blue key may be something to do with that if you can identify the flow meter brand?

The actuators are thermo-electric and take quite a few minutes to warm up the wax inside to open up the valve beneath them to allow water to flow in the loop under the floor. If they light up it suggests mains is getting to them (if not then that needs sorting, checking with a multimeter). They can and do fail. You may have some manual screw-on caps to operate the valve with actuator removed?

Yes close Flow and Return.
The air bleed valves are exactly that.
C are covers to seal the drain / fill ports. B are the valves to open/close those ports.

I'd probably remove the cover on the highest manifold (flow) only and (with a suitable container under) release the pressure from the UFH system via that... You don't want to drain off much if any water... Then the flow meters can be unscrewed (IF that's the right thing to do)?
Repressurise via the flow/return isolators and top up the boiler after.

Probably. I'd be inclined to not want to mess majorly with the system at the current (weather) time more than you have to! Check if the pipes are getting warm from water flowing, even if the meters are stuck at 0 ?

 

[MasterMark]

You need to find the install and operating instructions for your particular manifold, actuators and meters.
https://prowarm.com/pages/manuals may have them (or be able to identify what you have installed (as your flow meters look different to their current model), and may be another make altogether?


Thanks Rodders! I think it might be a "Reliance" model, branded prowarm. I'm ok with the process, but am failing at the first hurdle - the red and blue flow & return valves seem INCREDIBLY stiff and they won't budge. Assume they only go one way to close, and I should just be turning them clockwise 90 degrees? I can see a little nut and bolt inside the there that loosens the red/blue plastic knob itself. Should I try and remove the knobs completely and see if I can close the valve with them off? I can't find the instruction manual for this particular model, only a spec sheet (though that won't help me to open the valves anyway!)

 

[MasterMark]

ok, so i removed the plastic knobs and used a spanner to close the valves (90 degrees left / ANTI-clockwise). No way I could have done them without the spanner, way too tight.