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Old 04-03-11, 04:10 PM   #381
cholcombe
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Thanks Rich! Yeah I don't think I'm getting too crazy with the oversize of the system. We have 4 rooms connected together in a row. I think that if I get a bigger size unit I'll get a little more heat further down the hall.

I must say you all have been amazing with your responses here. I don't think I would have the guts to try this without your encouragement. I placed the order this morning

I'll check into the permit thing. That does seem awful suspicious.

Thanks,
Chris

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Old 04-03-11, 06:40 PM   #382
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Okay Chris! Good luck with your install. When I placed my order,
I was a bit nervous about being able get it done.
I knew DIY was a gamble, but I wasn't spending beyond my means.

I also knew it was something that would be helpful to our comfort and our budget,
if I could get it working. I had read where other guys had done it, so why not?

IMHO, investing in a modern mini-split is going to give you a better return
than buying a 3D HDTV or 2 or 3 ounces of gold.


I've starting playing with the idea of running the Sanyo off-the-grid, using solar
during sunny day time hours.
I know it would take years to break-even on the hardware, but I just like
the idea of being able to heat or cool my home for "free" or when the grid fails.

I have already accumulated most of the parts I'll need. Just have to find
out if my Sanyo will work with MSW or does it need true sine waves..

Life is short, so make mine an Adventure.

Cheers,
Rich
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Old 04-04-11, 12:29 AM   #383
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Quote:
Originally Posted by cholcombe View Post
I've looked at average temperature maps for Philadelphia. In Jan it's 25 degree's. That seems fairly decent to me. So I should design around that temperature is what you're saying right?
This is something that you might want to do some research on since you're going to be spending your money to heat your house.

However, from all the way over here in Portland, Oregon, I did some Googling around and came up with an outside design temperature of 14 degrees F for Philadelphia.

There's probably something in Philadelphia like an office of the State Department of Energy, or something similar. They are very likely to have statistical information on winter time temperatures where you live. They can probably tell you exactly what the proper outside winter design temperature is for your location. Fifteen minutes and a few phone calls and you will know for sure.

...but it's likely to be pretty close to 14 degrees F.

I found another bell curve picture:


...ignore the number on the bottom of the diagram, they are standard deviation numbers, nothing to do with what we are talking about.

So you said that the average temperature where you live is 25 F. On the bell curve picture, that would fall right in the middle of the bell curve, right where the black line is. If you sized your heating system for that temperature, your heating system would be able to provide heat for half of the days during the winter. The other half of the days, your heating system would be insufficient, so you'd be cold.

The design temp point is to be somewhere close to the red line I have drawn in the chart (imagine that the red line is around 16 degrees F). That way, your heating system will produced heat sufficient to keep your house warm on all but a small number of winter days. On those few days, your heat pump will not be able to provide heat as fast as your house is losing it.

With a heat pump, you want it sized a little smaller than your maximum demand, and on those really cold days ("blue northers" we call them) you would utilize a secondary heat source. Xringer uses his oil furnace. I close off parts of my house I don't absolutely need to heat, and if it gets really bad, I use an electric heater.

Some heat pumps have resistance heating wires built in. To my knowledge, no mini-splits have built in resistance heating wires... you'll have to provide the axillary heating with a wood stove, gas heater, electric heater, etc.

That should pretty much do it...

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Old 04-04-11, 07:24 AM   #384
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"Some heat pumps have resistance heating wires built in. To my knowledge, no mini-splits have built in resistance heating wires..."

I found out just a while ago.. There are a few of them on the market now..
I guess that's not a bad thing..
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Old 04-04-11, 09:01 AM   #385
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I've really learned a lot reading this thread. Oh I had another question. With the condensation line how does it work when you have the lines for the indoor air handling unit drop down from the ceiling? I didn't think it would drain properly.
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Old 04-04-11, 11:43 AM   #386
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I've really learned a lot reading this thread. Oh I had another question. With the condensation line how does it work when you have the lines for the indoor air handling unit drop down from the ceiling? I didn't think it would drain properly.
The indoor unit will have:
  • 2 copper refrigerant lines which have their circulation determined by the compressor. There is a limit though, to how much height difference (and lateral distance) the compressor can handle. Usually this isn't an issue.
  • 1 multi-wire cable that supplies electrical power to the inside unit, also sense wires that tell the outdoor unit whan to turn on & off. Except for the length of the cable, which could be replaced by a longer one, height restrictions do not apply.
  • 1 condensation tube which is totally dependant on gravity. There must be a continuous downward slope of the tube for it to drain properly, unless you have it slope downward into a collection tank and pump out the collection (automatically?) when it needs it.


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Old 04-04-11, 01:47 PM   #387
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Quote:
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I've really learned a lot reading this thread...
Another consideration when sizing your ASHP, when the outside temperature goes down, the amount of heat output that an ASHP can deliver also, unfortunately, goes down. This is different from a fossil fueled heat source or a ground source heat pump.

I generated a chart, based on some data that Xringer dug up, that should suggest this situation:


...so when the weather gets colder (and you need more heat), the ASHP has less heat to give.

So if your design temperature was for instance 16 degrees F, and you did a heat loss calculation and therefore knew you needed say, 12000 BTU to do the job, you wouldn't go for a 12,000 BTU unit, you'd need to go for an 18,000 BTU unit, because that would be the closest to do the job at 16 degrees F.

This would be adjusted for the reduction in efficiency as the outside temperature gets lower.

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Old 04-04-11, 07:48 PM   #388
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Quote:
Originally Posted by AC_Hacker View Post
Another consideration when sizing your ASHP, when the outside temperature goes down, the amount of heat output that an ASHP can deliver also, unfortunately, goes down. This is different from a fossil fueled heat source or a ground source heat pump.

I generated a chart, based on some data that Xringer dug up, that should suggest this situation:


...so when the weather gets colder (and you need more heat), the ASHP has less heat to give.

So if your design temperature was for instance 16 degrees F, and you did a heat loss calculation and therefore knew you needed say, 12000 BTU to do the job, you wouldn't go for a 12,000 BTU unit, you'd need to go for an 18,000 BTU unit, because that would be the closest to do the job at 16 degrees F.

This would be adjusted for the reduction in efficiency as the outside temperature gets lower.

Regards,

-AC_Hacker
Hi Guy's,

I have the opposite problem. I need to combat the heat. In image below the green square is the proposed cooling area. I'm thinking 80 in the summer and 70 in the winter. The summers are my main problem. Shop can reach 130 degrees inside and 115 outside. All walls, garage doors and ceilings are insulated. Looking at Sanyo 24,200 BTU Wall Mount Heat Pump Air Conditioner Kit. Is this doable or over kill?

Vern

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Old 04-04-11, 07:59 PM   #389
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Default Swamp Cooler?

Vern, can you use a Swamp Cooler? Maybe one you can drag into the area where you are working?

PAC2KCYC01 Port A Cool Commercial Swamp Cooler With Centrifugal Air Delivery System -

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Old 04-04-11, 08:28 PM   #390
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...Is this doable or over kill?

It all starts with a heat loss analysis, only in your case, a heat gain analysis...

Without that, it's just guesswork.

But the basics are the same:
  • Heat gain analysis
  • Design Temp
  • Heat Pump de-rating (I don't know where Xringer got the heating table he posted)

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