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Heat exchanger Question
Magicare
Member Posts: 1
I'm new here but wish I had found this site long ago.
I have designed and built an in floor hydronic heating system for a new
home I'm building in Ontario cottage country.
Because we are located where natural gas is not available one of the aims
of the new system is to take advantage of low rate electricity offered by
the Smart Meter System soon to launched in Ontario.
I am using a Monitron EH25 electric boiler to heat a 1000 gallon tank of
water which will be my energy reservoir. The boiler, through a closed
circuit with a heat exchanger, heats the tank of water up to 180F at night
when the power costs about 5.2c/ kWh. For a heat exchanger I'm using a
modified automotive radiator situated in the bottom of the tank.
This much is completed and works just fine.
The heat loss calculation for the house indicates that the maximum heat
loss to be around 60,000 BTU/hr.
I have built most of the 2 manifold distribution system with 4 zones of
250 feet on each mainfold but am still trying to figure out how large a
heat exchanger I will need for the heat distribution side of the system,
this will also be a modified automotive radiator.
Anyone have a calculation as to how many square inches of a copper water
to water heat exchanger will be required to extract 60,000 BTU/hr and
deliver an output temperature about 20 degrees cooler than the tank
temperature?
Perhaps a little more information would help.
The 160 degree water , from the distribution heat exchanger, will be
tempered using 3 Honeywell mixing valves before being sent to circulating
pumps then to throttling manifolds for the hydronic tubing. Three mixing
valves are used because of the differing types of floors being heated,
garage, slab on grade and engineered flooring on joists. The output
temperature from the mixing valves will be adjusted to a temperature
appropriate for the type floor being heated.
The tank water will not be circulated through either the boiler or floor
tubing because I'm using cast iron pumps which will require an inlet pressure of about 5 p.s.i. at these temperatures to prevent
cavitation. By using heat exchangers for both the boiler and distribution
circuits I'm able to prevent oxygen entering the water and will be able to
pressurize each of those circuits to establish the appropriate pressure at
the pump inlets.
The only thing I've not been able to get a handle on is the required
surface area of the distribution heat exchanger.
Thanks.
I have designed and built an in floor hydronic heating system for a new
home I'm building in Ontario cottage country.
Because we are located where natural gas is not available one of the aims
of the new system is to take advantage of low rate electricity offered by
the Smart Meter System soon to launched in Ontario.
I am using a Monitron EH25 electric boiler to heat a 1000 gallon tank of
water which will be my energy reservoir. The boiler, through a closed
circuit with a heat exchanger, heats the tank of water up to 180F at night
when the power costs about 5.2c/ kWh. For a heat exchanger I'm using a
modified automotive radiator situated in the bottom of the tank.
This much is completed and works just fine.
The heat loss calculation for the house indicates that the maximum heat
loss to be around 60,000 BTU/hr.
I have built most of the 2 manifold distribution system with 4 zones of
250 feet on each mainfold but am still trying to figure out how large a
heat exchanger I will need for the heat distribution side of the system,
this will also be a modified automotive radiator.
Anyone have a calculation as to how many square inches of a copper water
to water heat exchanger will be required to extract 60,000 BTU/hr and
deliver an output temperature about 20 degrees cooler than the tank
temperature?
Perhaps a little more information would help.
The 160 degree water , from the distribution heat exchanger, will be
tempered using 3 Honeywell mixing valves before being sent to circulating
pumps then to throttling manifolds for the hydronic tubing. Three mixing
valves are used because of the differing types of floors being heated,
garage, slab on grade and engineered flooring on joists. The output
temperature from the mixing valves will be adjusted to a temperature
appropriate for the type floor being heated.
The tank water will not be circulated through either the boiler or floor
tubing because I'm using cast iron pumps which will require an inlet pressure of about 5 p.s.i. at these temperatures to prevent
cavitation. By using heat exchangers for both the boiler and distribution
circuits I'm able to prevent oxygen entering the water and will be able to
pressurize each of those circuits to establish the appropriate pressure at
the pump inlets.
The only thing I've not been able to get a handle on is the required
surface area of the distribution heat exchanger.
Thanks.
0
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