Under Floor heating failing to start. Advice needed

[Highlandeagle]

Hello Everyone,
My first post hope I don't break any rules! but I am seeking advice on my wet under floor heating system which is about 6 years old in a new build of that age.
The system comprises of Camray 5 external oil fired boiler, circulating pump mounted on the boiler, basic temperature control also on the boiler.
Megaflo unvented mains pressure water heater with Honeywell 2 port valve on the primary circuit pipe, cannot find any other one.
7 zones, 4 downstairs and 3 upstairs each with digital 7 day thermostats which all appear to click on display correctly and demand heat.
Each zone has an actuator valve showing red.
New ufh circulating pump fitted correctly and confirmed as working.
Boiler responding to demand for HW but not for UFH.
Hot water present to one side of the pump and the mixer valve.
System pressure and temp OK.
It would seem that the heat call from the thermostat to the pump and the actuators is not operating the pump and opening the actuators.
This system has worked without fault until the pump failure which has been bled etc.

Could anyone with the knowledge of these systems suggest any way forward please?
NB. I have just discovered that there is no mains supply showing at the back of each thermostat is this the obvious problem or am I missing something else?

 

[SimonG]

What u/f system is it?

 

[Gray0689]

Yes if no power at stats then the heating won't come on to underfloor side as actuators won't open sounds like you have a fuse blown or a faulty wire somewhere

 

[aqualogic7]

some systems dont have high voltage at stats need to know what system

 

[stevetheplumber]

most ufch stats and actuators are low voltage

 

[Gray0689]

Yes but if hard wired there should still be power

 

[Highlandeagle]

Thank you all for the replies.
I think the system was constructed on site by a contractor using commonly available parts.
The thermostats are powered by dry batteries the rear contacts of which seem to go into electrical mains voltage wires
,thence to the terminal board where they contact with mains driven actuators which are marked 240v.
Having checked the security of the wires in the terminal box I can establish mains power from the breaker to the isolator switch and then to one terminal block in the box.
Since doing this one of the actuators shows open and the terminal shows 240v but the pump does not operate.
If I independently power the pump that zone heats and the respective thermostat will provide power to the terminal but won't operate the actuater.
Detaching each actuator does not replicate this situation with them.
Mystery!!!

 

[afenteman]

Actuators showing RED mean they are not open letting thus not letting any heat through. it is extremely rare for all the actuators to not work so there is a problem somehwere. Remove all actuators (they should unscrew) this should let water flow to all zones. You need an electrician in to see where the link is broken and to check everything is wired correctly. You may need a replacement wiring centre

 

[buckley plumb]

post some pics and makes it easy to identify. have you checked the zone valve on the ufloor manifold some have them some dont

 

[Highlandeagle]

Thank you all for your replies to my queries. Having spent the last couple of days with the meter in the two terminal boxes, one by the downstairs 4 zone manifold and one upstairs by the 3 zone manifold, I have at least established the wiring setup.
I still cannot get the pump to run if any one of the thermostats call.
I cannot get any zone valve to open via the thermostat calling except 1 zone, which shows 240v at the thermostat when calling for heat.
All others show closed.
This system does not have a wiring centre but has two terminal boxes as above.
There is switched power to the downstairs box but the only power to the upstairs box seems to come from the megaflo cylinder connections.
I have attached a couple of pictures if they prove to be any use.
Probably have to look up an electrician shortly.

 

[Gray0689]

It's a very home made set up I'm not saying its wrong just strange

 

[buckley plumb]

whats the plate heat exchanger for

 

[Nordio]

Looks like the boiler circuit is vented and the uf sealed and the plate is transferring between the two.