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Posted: Wed Aug 25, 2010 8:36pm

Post Subject: Central heating 'Gurgling" at startup

We have a Hurricane diesel heater that is controlled by a Heatmiser thermostat. The system includes a calorifier 4 radiators and a towel rail. It is less than a year old and quality equipment has been used throughout. Initially we had a problem with hydrosyphoning, in that when set to hot water only the radiators got warm until the thermostat in the calorifier cut off the "call for heat". This was cured by adding a discrete return pipe from the calorifier rather than the original common return. We now have the issue of the gurgling in what I believe is the last and occasionally second to last radiator in the system. It only lasts for the first few minutes and sometimes only briefly. I manage to bleed the radiators and get air out of the aforementioned radiators and the towel rail, which I think is the highest point. Not very much air comes out. I normal circumstances I would not repeatedly bleed them. I have not taken more than an egg cup of fluid out of the system yet put two pints into the expansion tank, which only varies about 2 inches from warm water to cold. I can find no evidence of leaks. The system was refilled after the extra return pipe was replaced and I continued to bleed for three weeks afterwards as I thought it might be difficult to get all the air out of the system straight away. Despite the bleeding (when cold), every morning the radiator gurgles. The boatbuilders are trying to work out the problem but I am not confident we have arrived at a solution. The pump I believe is on the return and there is an air trap so I dont know why the gurgling occurs. Do you have any suggestions. I hope to attach a diagram which is as per our boat except for the separate return and the extra radiator

Central heating 'Gurgling" at startup
Tony-B
Tony-B

Posted: Wed Aug 25, 2010 9:02pm

Post Subject: Central heating 'Gurgling" at startup

I am afraid that the diagram you posted is unreadable - as are most that get put on here. I also think that even if you emailed me the diagram direct AND added the modifications it would still not help much because I suspect one needs to inspect the system in 3D, not 2D. It seems Heatmiser produce a range of thermostats so I can not see what yours is supposed to do but I note that I did not see any that said they were for 12/24v DC operation. From what you say it seems you have had what is to my view an overcomplicated system installed. I suspect the heat distribution thing could have been easily and simply solved by the use of a three port, three position T valve giving you hot water, hot radiators or both Leaving a simple thermostat to control the radiator temperature and the boiler stat. to control the water temperature (I am sure the Hurricane must have a boiler stat). I doubt its anything to do with the heater and suspect you have a slight weep and air leak somewhere on the system - I trust you have checked the cabin bilge! However water may not show up in there for many months after the temperature drops enough to prevent evaporation. Those two pints minus an eggcup full have to have gone somewhere unless there is an awful lot of air dissolved in your water or trapped in the system. I suspect dye needs adding to the central heating water and the whole system carefully checked over months to see if a weep can be located. If the boatyard can not sort it out I suspect you will have to try o locate an older and very experience domestic central heating chap who relishes a challenge. I fear that if no weeps or loose joints can be found there is a system design problem. Sorry not to be much help. Tony Brooks

Mal-110
Mal-110

Posted: Wed Aug 25, 2010 10:40pm

Post Subject: Central heating 'Gurgling" at startup

Thanks Tony, I may have overcomplicated my illustration of our system, as the diagram would have shown(its a shame you cannot enlarge it) this system is as you describe there is a valve that shuts off hot water to the radiators at a time or when a certain temperature is reached. The hot water does the same, what we cannot have is radiators on and not the hot water unless its at temperature. I agree with you that the two pints must have gone somewhere, i was hoping that after the refill that the air and water around the system would settle after a series of bleeding. As its been very one we have not really had the heating on for long. Nevertheless I believe it should have sorted itself out by know. I aso think you are right in that a very experienced central heating engineer may have the answer but as out boat has been built using diagrams supplied by Hurricane and have been used by boatbuilders across the country added to the fact that our boat is not radically different design seems not to be the issue. I do have some experience and I came up with the separate return from the calorifier which works,(not rocket science). My theory is that either the air trap is causing the problem or that the pump would be better placed on the flow side rather tan the return. Your view welcome Thanks Malcolm Blundell Ps Ive tried to attach the image again but I suspect the receiving server blocks the full image coming over

Central heating 'Gurgling" at startup
Tony-B
Tony-B

Posted: Thu Aug 26, 2010 7:40am

Post Subject: Central heating 'Gurgling" at startup

If you are using Hurricane drawings a phone call to Calcutt Boats must be worth a try because even if it is nothing to do with the boiler the importers probably come across more problems than anyone else so have more experience. I think most circulating pumps have a maximum operating temperature which might be exceeded on the flow side of the boiler. I suspect the inertia of the water in the system might be causing a slight low pressure area as the pump starts allowing air to be drawn through a weeping joint but I have no real idea why the noise should be continuing. Lets hope other readers respond with something positive. Tony Brooks

Mal-110
Mal-110

Posted: Thu Aug 26, 2010 8:48am

Post Subject: Central heating 'Gurgling" at startup

Thanks again Tony, The boatbuilders assure me they have spoken to Calcutt and you are right its nothing to do with the heater. There was a concern that the hurricane thermostat was set too high but this was disounted by Calcutt, who cannot suggest a solution therefore one assumes the problem must be the design or instalattion of the system so I am back to the boatbuilders who are rather stumped. Kind regards Malcolm

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