Perkins 4236 (M90) Heat Exchanger For The Calorifier - Is There A Thermostat

[Deleted member 36384]

Hi,

My Rival is now launched after 2 1/2 years ashore. The engine started fine and has had a very long run, so all appears to be well.

After the long run the water from the hot water tank (calorifer) got very hot, hotter than I remember. The water is heated via a standard Perkins M90 heat exchanger. I have two hot water tanks, an electric immersion heater tank and the calorifier, both are connected to the pressurised water system. During the partial refit I removed the insulation around the calorifier because the insulation was damaged and contaminated with oily water residues, it was just loose wrap type insulation. The insulation has not been replaced. The only other change to the water system was new accumulator tank and bladder. The pressurised system works well.

When I went through my pre engine checks, the fresh water coolant in the header tank was lost but the engine still had plenty of coolant. So I topped that up.

I don't have my manuals at home with me but I am wondering if there is a thermostat in the hot water heat exchanger and if it has stuck in the open position. Also do you think the lack of insulation would cause the circulating water from the calorifer to continually circulate and end up very hot.

The engine temperature gauge was a stead 80 degrees celsius on the long run. Of course, my recollection may be wrong and I have always had water that is very hot.

Any thoughts would be appreciated.

BlowingOldBoots

 

[vyv_cox]

I have not come across an additional thermostat in a heat exchanger. There is sometimes a thermally controlled valve on the inlet to the calorifier to prevent it from becoming excessively hot. Calorifier cannot get hotter than the coolant in the engine of course but ultimately it will reach almost the same temperature assuming there is no control valve.

 

[VicS]

I have not come across an additional thermostat in a heat exchanger. There is sometimes a thermally controlled valve on the inlet to the calorifier to prevent it from becoming excessively hot. Calorifier cannot get hotter than the coolant in the engine of course but ultimately it will reach almost the same temperature assuming there is no control valve.

Or there may be a thermostatic mixer on the calorifier outlet to the hot water system.

one of these allows the maximum amount of heat to be stored in the calorifier but regulates to temperature of the water going to the taps

I believe there is an increasing trend for these to be fitted as standard.

 

[Deleted member 36384]

Thanks for your response. Reading the thread A Most Curious Problem and an observation when motoring through the Crinan Canal, where the temperature was less than expected, makes me wonder if I need to look at the thermostat and perhaps look at the coolant again. Perhaps the thermostat was not opening fully and then after the period of use is now stuck fully open.

 

[DickB]

I also have an M90 also with the cooling water being fed through the calorifyer. I don't have any thermostat in that circuit and like you the hot water eventually gats to 80 deg C. The engine has a thermostat as you would expect.

Its always been that way but I can understand that you might wish to limit that by adding in a thermostat.

cheers,

 

[Deleted member 36384]

Thanks all, it looks like after 2 1/2 years I have forgotten how hot the water gets. Normally the engine is not run for that length of time, 6 hours, but the weather last week was calm and it was the first run since being recommissioned. Probably no need to worry.

I had to tighten all the hose clips on the new hot water hose as it got quite soft and they were made up last winter.

Thanks again for your comments.