Using a Raypak E3T to heat 650 gallon hot tub in texas

[yrral_TX]

Hello, I'm was looking for non bias (or experience) on efficiencies of using a RayPak E3T (the 92 MBTU/h one) for a hot tub with about 650 gallons in terms of:
-- heating water temp = I saw in the forms that someone had said: 8 degrees an hour?
-- cost using electricity to heat water with this Raypak heater
-- how efficient is the raypak heater when elements are not optimal?

FYI: I don't have gas or propane
the old heat pump hasn't worked in long time. When it "did" work... it was nice that the water would get to 102
HOWEVER, years ago.. I didn't care or worry about cost, efficiencies, etc. I'm wiser now...or at least I'm older.

So looking at getting any heater and the lowest cost... yeah, I'm smarter now?

NOTE: I understand that even when the old heat pump worked, if the humidity was low and temp was cold (winter time)...
10 hours of running the heater would not heat the water more than a few degrees => frustrating, I remember those days.
WHY IN THE WORLD would some add a heat pump to the pool hot tube when it can't heat the water????

anyway, i'm thinking:
- technology has improved?
- there are better solutions?

I just need to ask people who know facts and/or solutions
which is why I posted this...
THANKS!!!

E3T – Raypak

Raypak Pool & Spa, Residential and Commercial Hydronic Products -

www.raypak.com

 

[yrral_TX]

@DrewLG
I saw Drew say this in another thread:

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The biggest heater you're likely to find will have an input rating of 400,000 BTU/hour. Propane will produce 91500 BTUs per gallon, so that heater uses 4.4 gallons of propane per hour. At, say, $3 per gallon, it'll cost you $13/hour to run the heater.

Heaters are approximately 80% efficient, so that one will put out 320K BTUs per hour. One BTU will raise the temperature of one pound of water by one degree F. You have 13500 * 8.3 = 112050 pounds of water, so your heater will raise the hot tub's temperature 320000/112050 = 2.8 degrees F per hour.

At 2.8 degrees/hour, heating from 30F to 104F will take over 25 hours. At $13/hour, that will cost over $325.
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Uhmmm, what are the factors/items I need to do some valid calculations?

raypak:
92 MBTU/h

I'm not sure how to figure out the calculations for various examples to heat our hot tub

thanks

 

[ajw22]

650 gallons X 8.3 lb/gall = 5,395 lbs of water

1 BTU can heat 1 gallon of water 1 degree

92,000 BTU/ hour can heat 5,395 lbs of water 17 degrees in an hour assuming no heat loss to the air.

Electric heaters are 100% efficient.

Can you provide three 40 amp circuit breakers for the 92,000 BTU heater?

 

[yrral_TX]

SWEET!!!!!! 17 degrees an hour
thank you.

I saw there are already two 40 amp... assuming those are going to the existing heat pump.
The control board/box needs to be redone anyway.... as it is old and things are not working.
I'm guessing/hoping/thinking... surely a 3rd one can be added?

 

[ajw22]

SWEET!!!!!! 17 degrees an hour
thank you.

I saw there are already two 40 amp... assuming those are going to the existing heat pump.
The control board/box needs to be redone anyway.... as it is old and things are not working.
I'm guessing/hoping/thinking... surely a 3rd one can be added?

Have a licensed electrician confirm that load can be added.

How many amps is the main electrical service to your house? Some houses only have 100amps, 150 amps, 200amps of electrical service and that heater alone will take 120amps.