Sverige
A Brit in Sweden
Hi all,
I see a few threads in this section which cover this subject, but nothing which seems fully relevant to my circumstances. I am trying to research what might be the best approach to make use of solar to heat water for showering during the 9 months or so each year when we have enough sunshine here in Sweden.
I think I can rule out options which use PV panels and electrical heating of the water. There are 2 reasons, first my available space for PV panels is already consumed and the output of those panels doesn’t give me the kind of excess which water heating would need. Second, my existing hot water installation is a ground source heatpump system which I can’t run on my solar electricity as it needs a 3 phase supply and my inverter is single phase and paying for a big expensive 3 phase inverter is off the table.
So.. I’m exploring solar thermal systems and I see it’s normal to have some kind of collector panel with an antifreeze fluid then to make use of a heat exchanger to warm water in a collector tank. Well my ground source heat pump already has a hot water tank conveniently plumbed into all the taps and the shower in the house, so really it’s the water in that tank which I would like to heat up.
I can think of two different ways to do this, and I don’t know what’s best. First, I could use the warm antifreeze fluid from a solar collector to warm the brine which comes out of the ground, so my heatpump is then using that much warmer input fluid to heat my hot water and in doing so, will use much less electricity (but still some). Is this feasible? I don’t know - I’d better try to find out what brine temperature range my heatpump can operate with, as it normally only receives fluid in the range 0-8C which comes from the borehole in my garden.
Option 2 is to apply a heat exchanger to the output side of the heatpump system and with the use of a circulating pump to slowly extract energy from the solar collector circuit and warm up the water in the water tank itself. I like this option as the big energy thief heat pump can remain switched off all summer and I only have to electrically power a small circulating pump, which my existing PV panel installation would cope with.
Whichever option I choose, I would need to rig some kind of heat exchanger transfer the heat from the solar collector circuit into either the brine (ethanol) circuit or the hot water pipes. This might just be running the pipes from the solar thermal circuit directly alongside the other pipes, as in both cases I have about 5m of copper pipe length exposed within my garage ceiling area. Does anyone have experience or info on such a DIY heat exchanger where pipes are just laid alongside each other?
Edited to add concept sketch :
I see a few threads in this section which cover this subject, but nothing which seems fully relevant to my circumstances. I am trying to research what might be the best approach to make use of solar to heat water for showering during the 9 months or so each year when we have enough sunshine here in Sweden.
I think I can rule out options which use PV panels and electrical heating of the water. There are 2 reasons, first my available space for PV panels is already consumed and the output of those panels doesn’t give me the kind of excess which water heating would need. Second, my existing hot water installation is a ground source heatpump system which I can’t run on my solar electricity as it needs a 3 phase supply and my inverter is single phase and paying for a big expensive 3 phase inverter is off the table.
So.. I’m exploring solar thermal systems and I see it’s normal to have some kind of collector panel with an antifreeze fluid then to make use of a heat exchanger to warm water in a collector tank. Well my ground source heat pump already has a hot water tank conveniently plumbed into all the taps and the shower in the house, so really it’s the water in that tank which I would like to heat up.
I can think of two different ways to do this, and I don’t know what’s best. First, I could use the warm antifreeze fluid from a solar collector to warm the brine which comes out of the ground, so my heatpump is then using that much warmer input fluid to heat my hot water and in doing so, will use much less electricity (but still some). Is this feasible? I don’t know - I’d better try to find out what brine temperature range my heatpump can operate with, as it normally only receives fluid in the range 0-8C which comes from the borehole in my garden.
Option 2 is to apply a heat exchanger to the output side of the heatpump system and with the use of a circulating pump to slowly extract energy from the solar collector circuit and warm up the water in the water tank itself. I like this option as the big energy thief heat pump can remain switched off all summer and I only have to electrically power a small circulating pump, which my existing PV panel installation would cope with.
Whichever option I choose, I would need to rig some kind of heat exchanger transfer the heat from the solar collector circuit into either the brine (ethanol) circuit or the hot water pipes. This might just be running the pipes from the solar thermal circuit directly alongside the other pipes, as in both cases I have about 5m of copper pipe length exposed within my garage ceiling area. Does anyone have experience or info on such a DIY heat exchanger where pipes are just laid alongside each other?
Edited to add concept sketch :
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