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Solar Heat Pump Combi
Pincher
Posts: 6,552 Forumite
I am thinking about heat collection as well as heat dumping.
I know that vacuum tube solar thermal panels will not dissipate heat, but how about flat plate exchangers?
I would like to collect heat for a heat pump, or to dump excess heat using the same panel, for summer time.
The heat pump compressor is also connected to the underfloor heating manifold via a pair of flow/return pipes (and possibly heat exchanger, in case of glycol/water system), and to the thermal store via another pair of flow/return pipes.
A set of thermostats located strategically will allow the control electronics to work out the most efficient way of using the available components to achieve the target temperatures for the rooms, as well as hot water.
The pumps should be reversible, so that the flow through the thermal store changes direction depending whether we are withdrawing heat or storing heat.
Summer
======
The main benefit is in summer, when we want room chilling, we use the heat picked up to heat the thermal store. Mains pressure cold water picks up the heat to become Domestic Hot Water. When the thermal store cannot take any more heat, we divert the heat to the roof exchanger panel, switch on a few fans to dissipate the heat.
When the rooms have been cooled to the set point, or cooling is simply not switched on, we check for solar temperature. If solar input temperature is greater than the thermal store, we turn on the pump, but NOT the compressor, to allow solar heating of the thermal store.
Winter
=====
We use the system in classic air source heat pump mode, to provide Domestic Hot water and under floor heating, but with a twist. We reverse the flow to the thermal store during heat exchanger defrost, so we do not need to use an electric heating element. The idea is if it takes 3kWh of electricity to defrost the panel, we can use 3kWh of heat from the thermal store instead. At COP=3, that 3kWh was produced using 1kWh of electricity! With transfer loss and pumping, it should still be half the cost of defrosting by electric element.
There should be a small amount of solar input even in winter,
which we will try to use as much as possible. So the control system should be attempting to warm up the thermal store during the day as much as possible. At night, we can run the underfloor heating by running heat pump/roof heat exchanger, with the thermal store taking over during defrost.
We are looking at quite a complicated set of scenarios, and we need to allow manual intervention, in case we want heating instead of hot water: so don't really want to create a fuzzy logic controller myself.
Just to summarise:
1. Combined solar panel/heat exchanger.
2. Bare heat pump with triple flow/return manifold in a harness with reversible flow pumps and diverter valves capable of supportng the flow directions I described.
3. Fuzzy logic controller with manual override.
4. Differential temperature comparator using analogue inputs, not just on/off. Borrow from solar pump controllers.
5. Gledhill already does a heat pump compatible thermal store,
but you could do one matched to the controller. proprietary means you can charge what you like.
Come on, Mitsubishi, you can do it. I want it brought to market by April 2011, in time for the RHI subsidy.
Just give it a snappy name, like gas boiler combis, why don't we call it Solar/HP combis?
I know that vacuum tube solar thermal panels will not dissipate heat, but how about flat plate exchangers?
I would like to collect heat for a heat pump, or to dump excess heat using the same panel, for summer time.
The heat pump compressor is also connected to the underfloor heating manifold via a pair of flow/return pipes (and possibly heat exchanger, in case of glycol/water system), and to the thermal store via another pair of flow/return pipes.
A set of thermostats located strategically will allow the control electronics to work out the most efficient way of using the available components to achieve the target temperatures for the rooms, as well as hot water.
The pumps should be reversible, so that the flow through the thermal store changes direction depending whether we are withdrawing heat or storing heat.
Summer
======
The main benefit is in summer, when we want room chilling, we use the heat picked up to heat the thermal store. Mains pressure cold water picks up the heat to become Domestic Hot Water. When the thermal store cannot take any more heat, we divert the heat to the roof exchanger panel, switch on a few fans to dissipate the heat.
When the rooms have been cooled to the set point, or cooling is simply not switched on, we check for solar temperature. If solar input temperature is greater than the thermal store, we turn on the pump, but NOT the compressor, to allow solar heating of the thermal store.
Winter
=====
We use the system in classic air source heat pump mode, to provide Domestic Hot water and under floor heating, but with a twist. We reverse the flow to the thermal store during heat exchanger defrost, so we do not need to use an electric heating element. The idea is if it takes 3kWh of electricity to defrost the panel, we can use 3kWh of heat from the thermal store instead. At COP=3, that 3kWh was produced using 1kWh of electricity! With transfer loss and pumping, it should still be half the cost of defrosting by electric element.
There should be a small amount of solar input even in winter,
which we will try to use as much as possible. So the control system should be attempting to warm up the thermal store during the day as much as possible. At night, we can run the underfloor heating by running heat pump/roof heat exchanger, with the thermal store taking over during defrost.
We are looking at quite a complicated set of scenarios, and we need to allow manual intervention, in case we want heating instead of hot water: so don't really want to create a fuzzy logic controller myself.
Just to summarise:
1. Combined solar panel/heat exchanger.
2. Bare heat pump with triple flow/return manifold in a harness with reversible flow pumps and diverter valves capable of supportng the flow directions I described.
3. Fuzzy logic controller with manual override.
4. Differential temperature comparator using analogue inputs, not just on/off. Borrow from solar pump controllers.
5. Gledhill already does a heat pump compatible thermal store,
but you could do one matched to the controller. proprietary means you can charge what you like.
Come on, Mitsubishi, you can do it. I want it brought to market by April 2011, in time for the RHI subsidy.
Just give it a snappy name, like gas boiler combis, why don't we call it Solar/HP combis?
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