Downstairs radiators intermittently not heating up

[ro63rto]

Parents house, heating was fine for a month. Suddenly, all the downstairs rads (five) were stone cold in the morning while the upstairs (six) ones were nice and hot. This happened two mornings in a row. While this happened, the circulation pump was not running and I thought ok I'll replace the pump (tried spinning the impeller and it moved easily). The third morning all was normal, upstairs and downstairs worked and continued for four more days.
This morning, downstairs were stone cold again.
Could it still be the pump ? I read somewhere online someone said they changed the room thermostat and all was working again but I'm dubious.

Boiler is old on/off style, no Honeywell diverter valves at all, digital HW/CH timer and an oooold EKCO room thermostat.

Thanks for any and all help in advance.

 

[terryplumb]

Is the pump running or not when upstairs rads are hot and downstairs cold ?
Definitely no zone valves ?

 

[ro63rto]

Is the pump running or not when upstairs rads are hot and downstairs cold ?
Definitely no zone valves ?

No, pump not running when upstairs rads are hot

Definitely no zone valves. Boiler is an Ideal E-Type.

 

[Stuckinarut]

If the pump isn’t working, then something isn’t telling it to run

 

[ro63rto]

If the pump isn’t working, then something isn’t telling it to run

That's what I thought but not knowing what actually activates the pump when the timer clicks on I don't know what to check/replace.

 

[terryplumb]

The pump is either receiving voltage and not running ,or it's not receiving voltage. The next time it should be running and isn't,check voltage at the pump. Is there a wiring centre / junction box on the system? What provides your domestic hot water ?

 

[ro63rto]

The pump is either receiving voltage and not running ,or it's not receiving voltage. The next time it should be running and isn't,check voltage at the pump. Is there a wiring centre / junction box on the system? What provides your domestic hot water ?

I did take the lid off the box on the side of the pump but the sheathing on the conductors at so thick that they completely block the probes from my multimeter from getting to the wires etc.

Where does the voltage come from to activate the pump? Direct from the timer box or from the old EKCO room thermostat?

Hot water used to be provided by the boiler and stored in the immersion heater in their bathroom but now they are having to use the element in the tank as I suspect there is a blockage in the coils.

The whole lot needs a revamp but it will cost a fortune which as pensioners they don't have.

 

[terryplumb]

Is there a wiring centre or junction box on the system ?
If the boiler, historically ,was used to heat the hot water cylinder ,what controlled the different demands for heating / hot water,and hot water temperature ?
Follow the cable from the pump to establish where it connects to if possible.

 

[ro63rto]

Is there a wiring centre or junction box on the system ?
If the boiler, historically ,was used to heat the hot water cylinder ,what controlled the different demands for heating / hot water,and hot water temperature ?
Follow the cable from the pump to establish where it connects to if possible.

There's wires everywhere in the garage where the boiler and pump is. There's a set of wires that go through the wall in a plastic pipe, under the concrete conservatory floor, under the kitchen floor and up the wall in the breakfast groom into the timer that calls for heat or (used to) hot water.

The EKCO room stat is on the wall in the hallway with wires that go into the wall. Nothing is surface mounted in the house.

The cable for the pump goes into the boiler, disappears but I think it comes back up the front and into the box where the temp dial is, second from left.

 

[terryplumb]

Ok the thermostat box is where the pump gets voltage from,but you still need to establish if it's getting voltage when it doesn't run. A non contact voltage sensor would at least give an indication ,although it wouldn't of course tell you if the neutral was intact.
Show us a pic of wiring connections inside pump.

 

[ro63rto]

Ok the thermostat box is where the pump gets voltage from,but you still need to establish if it's getting voltage when it doesn't run. A non contact voltage sensor would at least give an indication ,although it wouldn't of course tell you if the neutral was intact.
Show us a pic of wiring connections inside pump.

Thanks for the info.
I've left my parents home for today, will be back tomorrow to get more photos. Don't have a non contact sensor but I'll see about finding my thinner multimeter probes to see if they will fit past the sheathing in the pump wiring.

 

[ro63rto]

Ok the thermostat box is where the pump gets voltage from,but you still need to establish if it's getting voltage when it doesn't run. A non contact voltage sensor would at least give an indication ,although it wouldn't of course tell you if the neutral was intact.
Show us a pic of wiring connections inside pump.

Ok, had to wait in for a delivery yesterday so didn't get a chance to go to mum's.
Here's the wiring inside the pump. Couldn't find my thinner probes, no idea where they are.

 

[Stuckinarut]

Wiring appears ok, apart from the earth/CPC, but afaik shouldn't really affect it running.

 

[ro63rto]

Wiring appears ok, apart from the earth/CPC, but afaik shouldn't really affect it running.

The earth Is there, it just has that oversized sleeve on it. Annoyed I can't find my needle probes for the MM.

 

[terryplumb]

Get two short pieces of insulated cable, and two insulated connector blocks,turn mains power off. Release the live and neutral conductors from the pump, put them into separate connectors and add the short lengths into the pump. You can then test on the connector blocks terminals.