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Kw HR ESTIMATE TO COOL A CHURCH 132'l x 60'Wx 55'h - 70 DEGREES IS TARGET -

ELISEUS

Apr 28, 2018
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HOW MANY HEAT PUMPS [ WATER EXTRACT CLOSED LOOP GEO THERMAL TO COOCL OUR CHURCH?
 

BobK

Jan 5, 2010
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Zero, if it never gets above 50 degrees outside.

Seriously, there are so many variables that would effect this, that I think you would need an HVAC expert to evaluate the site.

Bob
 

ELISEUS

Apr 28, 2018
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Zero, if it never gets above 50 degrees outside.

Seriously, there are so many variables that would effect this, that I think you would need an HVAC expert to evaluate the site.

Bob
i have a geo thermal hvac engaged- the speed bump is how many kilowatts do i need to deliver 100 ton of cooling- - you pick the heat pump [ - give me your est of how much juice to lift and maintain for 1 hr the inside of the big box church? 140kWatt hrs? lets assume it is 85 outside and sticky 60%RH ?
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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It depends on how long the refrigeration heat pump runs, which depends on the temperature difference between outside air temperature and temperature inside the church, as well as the relative humidity and how much water you must remove from the circulating air to reduce the RH to a desired level, and how often you exchange the air in the church with outside air, and how much thermal insulation the church has, and how much heat load a full congregation in attendance adds. You may also want to re-heat the air after reducing the moisture content, so factor in the power to do that.

When the heat-pump is supplying 100 tons of refrigeration, it will require about 352 kilowatts according to this calculator.

As mentioned by @BobK in post #2, you should hire an HVAC expert with proper instrumentation to test and evaluate your cooling needs. This is not a job easily performed by inexperienced amateurs.
 

ELISEUS

Apr 28, 2018
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It depends on how long the refrigeration heat pump runs, which depends on the temperature difference between outside air temperature and temperature inside the church, as well as the relative humidity and how much water you must remove from the circulating air to reduce the RH to a desired level, and how often you exchange the air in the church with outside air, and how much thermal insulation the church has, and how much heat load a full congregation in attendance adds. You may also want to re-heat the air after reducing the moisture content, so factor in the power to do that.

When the heat-pump is supplying 100 tons of refrigeration, it will require about 352 kilowatts according to this calculator.

As mentioned by @BobK in post #2, you should hire an HVAC expert with proper instrumentation to test and evaluate your cooling needs. This is not a job easily performed by inexperienced amateurs.
 

ELISEUS

Apr 28, 2018
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thank you for the calculations and table. and the time to reply comprehensively
I have a leading Geo therm design and install engineering firm engaged on this but did not fully appreciate their slowness to put a proposal on the table. until now i did not fully appreciate the complexity of the project undertaken. - we're trying to back up the heat pumps with a photo voltaic 'farm'. sizing the farm is my primary impetus in writing - my search continues but it appears it may be too early to replace our collapsing steam system. pls keep us in mind..... any chance the calculations are intended for an inhabited office space ; recall worship service is only for an hour - folks leave their coats on in the heating season and relatively cooler in the heat.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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With due diligence, and a LOT of reading, you can probably figure out how to solve your solar array sizing problem. Unless you have a huge bank of storage batteries for the solar panels to dump electrical energy into, it is doubtful your panels will be sized with enough capacity to back up a geothermal heat pump. A 100 ton cooling system means it is capable of moving enough heat to melt 100 tons of ice per hour, and that requires about 350 kilo-watts of continuous power expenditure, no matter how the heat is moved.

For example, each living human being creates approximately the heat produced by a 100 watt light bulb. So a small congregation of fifty souls is going to require that you move 5 kilo-watts of heat while they occupy the church. That heat has to go somewhere, whether folks worshiping in church are wearing coats or not.

Our bodies have an excellent "closed loop" temperature control system that is pretty effective in dumping our body heat into the surrounding environment to maintain a constant body temperature near 98.6F... on an average day (not too hot, not too cold) and with good health. The surrounding environment, that is, the air in the room, accepts our body heat while an air-conditioning system removes the heat we added to the air and dumps that heat outside. In the process of maintaining a constant temperature in air circulating within a room, an air-conditioner may also remove moisture from the air, condensing it as a liquid and lowering the relative humidity of the air. This process takes additional energy to convert water vapor in air to liquid water.

Additional heat always leaks into the church from the outside... through the walls, windows, roof, and through small gaps between doors and door frames, and small gaps between windows and window frames. It is probably impossible to prevent all drafts in a building, nor is that particularly desirable from a health point of view. You do need to circulate some fresh air from the outside to replace stale air on the inside of the church. There are published guidelines on how many air changes per hour are required. SInce the outside air is likely to require cooling, being warmer than the air inside the church, that is an additional heat load on the refrigeration system.

I haven't looked at the thermodynamic theory, or the math involved, with sizing refrigeration systems since taking courses in college during the 1970s. It is important to neither oversize nor undersize the system. Too much cooling capacity will mean too little time operating the compressor for good efficiency, a phenomenon called "short cycling". Too little cooling capacity will mean the compressor will run more or less continuously and may never be able to cool the church to a desired temperature. Having a heat-pump does help increase electrical efficiency, but that is a separate issue that has nothing to do with how the cooling system is sized.

And finally, you need some way to prepare the interior temperature of the church for services using appropriate sensors and controls. You don't want to "cool down" too early because that wastes energy. But you want the church to be comfortable when the parishioners begin to arrive, and to "automagically" cut back on the cooling when the building is unoccupied.

it appears it may be too early to replace our collapsing steam system.
Are you using steam to drive an ammonia-cycle refrigeration system? How is the steam generated? Why is the system collapsing? Back in the day, when Coal was King, steam plants were THE way to heat and cool large campuses. Wright-Patterson AFB near Dayton, Ohio had a huge coal-fired steam plant and miles of insulated steam pipes covering several square miles of the base. Downtown Dayton also supplied coal-fired commercial steam to most of the buildings there. It's a wonderful way to move heat around if you can afford to generate high-pressure steam. Steam tunnels are always warm and toasty, even on the coldest winter days.
 
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