AllenCherry

Dear Sharpener, Many thanks for your help! I will be back in Japan over Christmas, and will carry out tests on the water, Thanks also for your guidance on the pumps - again, I will do some research at various builders merchants to what is available. It seems that 'central heating' is uncommon in Japanese homes - they use hot air or full air conditioning as a norm. I'll let you know how I get on! Best wishes, Allen

Thanks everyone for your help! Please may I ask a few more questions? If the ph of the spring water is virtually '7' (i.e. neutral), then will it be possible just to pump the hot spring water around the heating system? If so, is there a suitable self-priming or submersible pump that could be used? The top floor of the house will be about 25ft above the surface of the spring. Ideally, the pump should be 12 / 24 volts to avoid the problems of the 100 volt 50Hz Japanese power supply - although a transformer could be used to change the mains voltage. Thank you in advance, Allen

Hi Sharpener, Many thanks for your comments! You mention: >> conventional HX << What do you suggest as a 'conventional heat exchanger'? From what I see, all other heat exchangers appear to need a pump for both the primary and the secondary circuits - would the pump on the primary side need to be 'rather special' to withstand the slightly acidic nature of the hot spring water? Thanks for your help, Best wishes, Allen

Wow! THANK YOU everyone for all the help! A bit more information - the house is in the countryside of Japan (Myoko), and has no 'central heating' at all - heating during the winter is by a few paraffin heaters, gas and electricity in each room. The hot spring water flows into a 'holding tank' before filling the hot spring bath (a Japanese 'onsen'), and I was considering using a stainless steel heat exchanger immersed into the 'holding tank' - something like: https://www.cotswoldkoi.co.uk/product/submersible-stainless-steel-heat-exchangers/?attribute_size=Large+30kw&gad_source=1&gclid=CjwKCAjwufq2BhAmEiwAnZqw8hz-OZ0nZzfeIwPXz-Yf88Oxf4soCF1pnL5h-Lfiwm6P1luhYeXrJRoC9yUQAvD_BwE The spring water does have some sulphur content, but is not very corrosive - so the stainless steel for the heat exchanger should be OK. Given that the water circulating around the radiators will obviously be less than 50 deg C, how do I work out the size of the radiators for the room size? The house is well insulated - the Japanese do things correctly! Another problem is the mains power is 100 volts 50Hz AC - so pump selection may be difficult. Can anyone give some ideas on the piping to use - will plastic be OK? Presumably an expansion tank will be required for the circulating central heating water, and the water will have to have anti-freeze added. Is a 'header tank' required, or can it be a closed-loop system? I really am appreciative of all the help - and yes, it is an exciting project, but I am an electronics engineer, not a central heating engineer!! Thank you, Allen

Anyone who help? I have access to a hot spring, temperature of the water is 50 - 55 deg C and the flow rate is 4 litres per minute. The hot spring is actually inside the house. Can this be used with a heat exchanger to heat radiators in various rooms? Will a heat pump be needed? Any advice will be very gratefully received, Thank you in anticipation, Allen Cherry