pauljordan Registered User

I have had a stove (Hunter) installed for a few months now and I have experienced problems with air getting into the system.

I originally had an oil burner installed in a pressurised system. Since then I have had a plumber install the Hunter stove. At first I presumed that it would take a while for the air to work its way out of the system through regular bleeding - this is something that I would expect.

Prior to the stove installation I never had a problem. I have checked all visible joints and they all seam fine - no leaks. The air seams to accumulate in the top of the stove. When I have a fire in the stove sometimes the water gets very hot and the thermostat does not kick in. If I then lower the temp on the thermostat then the pump switches on and I get a bubbling, gurgling noise from the system. I've attached a diagram of my setup to the post. Note that the bottom of the boiler is lower than the top of the stove, could this be an issue?

Any help is much appreciated.

Stove Layout.jpg
PeteHeat Registered User


There are no issues with the boilers in Hunter Stoves, they are professionally designed and working for years in thousands of homes.

Did you switch from the pressurised system to Open Vent (baby tank in the attic) ?

If not you have a very dangerous system and the best advice would be Do Not Use The Stove.

If it was changed to open vent does the system feed through the return or was it combined into the vent ? as silly as it appears it was not all that unusual.

Does your pump work into the boiler return or out of the flow at the top ? not a big issue with a pressurised system but makes a difference on open vent.

If the stove fills through the return it should automatically clear the air from the stove through the flow / vent as it fills.

Gurgling noises can be caused by the stat being set too high and if there are a few bends on the flow the hot water in the stove is not able to rise as easy as it should in a gravity system.


pauljordan Registered User

Thanks PeteHeat. Yes the system is open vent with a small tank installed in the attic. The pump feeds into the bottom pipe on the stove. The system feeds through the return and there is a seperate vent. I suppose this is so that if the water gets so hot in the stove and the pump doesn't come on for a particular reason the resultant pressure has an escape route?

I have the stat about 6" from the stove and the water only travels through one 90 degree bend from the stove to where the stat is. I have the stat set to 50c. Is this too high? If I set it lower than 50c, and as the stove cools, won't the water in the rad circuit start taking heat from the hot water cylinder? What would be an ideal temp to set the stat too?

PeteHeat Registered User


As the water heats in the stove it rises and is replaced by the water in the return circuit, so if the pump failed the hot water will vent off into the header tank and that water is replaced with cold water from the tank.

It is not unusual for a pipe stat to "Off" by as much 10% so your 50c setting may really be 55c, they also have a small differential built in to prevent On / Off cycles.

Move the temperature back to 45c and it should improve if not fix the problem, you can then tweak it a degree at a time to achieve perfection.


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