Busted Pump?

Belongamick

Hi,
Looking for advice:


Our 15 year old central heating system is an external oil fired Firebird boiler. There are two Zones electrically controlled by valves. Two thermostats in the house, one upstairs and one downstairs.


Decided (in my wisdom) to flush/clean the central heating system - had one or two radiators not warming properly.
Drained all water down.
Refilled with cleaning additive and started boiler - Fun started!
Boiler ran and stopped within 5 mins. Pump 'seems' to be running.
Zone Valves respond to thermostat settings - no hot water.
When boiler run there is some pressure in the system. I can vent the
radiators in the bottom of the house.

Pressure in the top of the house is poor - with the vent open there is
some air but no water coming out of the vent.
Checked the attic - no issues with feeder tank but water was not too
clean.

I'm not convinced that the pump is 100%.
When running, I opened the large screw in the front to check if it was spinning. Put a small screwdriver in to check for motion and it was turning.
Plenty of heat around the boiler - so much so that the thermostat tripped once which I reset.

The Pump sounds like its straining when running at the moment - no heat inside the house. Is there any way to completely rule in or rule out the pump or is it change it and see how it goes? Suggestions welcome...

Wearb

At a guess it might be that boiler is full of air.

John.G

Belongamick wrote: »

Hi,
Looking for advice:


Our 15 year old central heating system is an external oil fired Firebird boiler. There are two Zones electrically controlled by valves. Two thermostats in the house, one upstairs and one downstairs.


Decided (in my wisdom) to flush/clean the central heating system - had one or two radiators not warming properly.
Drained all water down.
Refilled with cleaning additive and started boiler - Fun started!
Boiler ran and stopped within 5 mins. Pump 'seems' to be running.
Zone Valves respond to thermostat settings - no hot water.
When boiler run there is some pressure in the system. I can vent the
radiators in the bottom of the house.

Pressure in the top of the house is poor - with the vent open there is
some air but no water coming out of the vent.
Checked the attic - no issues with feeder tank but water was not too
clean.

I'm not convinced that the pump is 100%.
When running, I opened the large screw in the front to check if it was spinning. Put a small screwdriver in to check for motion and it was turning.
Plenty of heat around the boiler - so much so that the thermostat tripped once which I reset.

The Pump sounds like its straining when running at the moment - no heat inside the house. Is there any way to completely rule in or rule out the pump or is it change it and see how it goes? Suggestions welcome...

Do you know where the cold feed is teed into the system?, I too have a 15 year old Firebird with a vented system but the cold feed is teed into the vent as it passes up and over the F&E tank (combined cold feed & vent). On the very few occasions that I have drained it down, on refilling I nearly always get air trapped in the top of the boiler and I vent it simply by opening the PRV on top of the boiler, some say that the PRV can leak afterwards but mine certainly never has in 15 years.
You could also remove the pump head and inspect the impeller vanes and pump ports for sludge build up which may have settled there after your cleaning.
The cleaning may also now have caused a blockage where the cold feed tees into the system so suggest get someone to watch the level in the F&E tank while you open the boiler drain fully, 5 litres or so should show if the F&E tank ballcock is making up to prove no blockage here.

Also vent the rads with boiler/circ pump off, initially at least.