Hi, We're just outside of Boston too, and we put in a pool last year. We do not have access to gas, so we put in an electric heat pump.
Pros :
1:
It really works! It is like a reverse air conditioner. However, the pool water will cool down overnight, or you could run it overnight. We did not run it overnight at all this cold summer. I set it for 80 and it ran a lot in the May, June, August and September, but...
2:
I was surprised that our electric bills were not as high as I thought they would be.
3. You don't have to deal with a propane company, or extra plumbing charges to hook it up to your main gas line.
Cons:
1:
It is big! But we have a good landscaper who did a nice job with disguising the pool equipment.
2:
We found that many pool service companies are extremely loyal to gas in New England and claim to know nothing about these types of pool heaters. Since the warranty is only one year, we might be stuck trying to find someone to service it, if we have problems. I think the heat pumps are way more popular in other regions of the country.

Overall we're happy with it.

Most heat pumps have a 10 year on the heat exchanger and 5 on the compressor. Most HVAC companies can service non warranty calls.

Scott

A heat pump will work fine so long as it is not too cold, there is not much wind, and you are not in a hurry. They are very efficient but slow. While a nat gas heater will heat a spa in 30 minutes, it will take 3-6 hours for a heat pump to do the same job. If the temp is below 50 and/or there is wind, your pool will never get warm. But I don't know who would want to swim in 50 degree weather. A heat pump is best at maintaining heat in a pool once it reaches 80 degrees. The warmer the outside temperature, the better and faster it will work. I like the Gulf Stream heat pump. Great product; great service. I have been in the pool and pond industry for 28 years.

http://www.magnoliaponds.com/

Spam isn't allowed here.

Just compare the btu/hour each can put into the water at 80% effectiveness and do the math- gas puts out a lot more btu.

100btu/hr vs 340btu/hr

Combine this with evaporation, and the water seeking the air temp 24/7 this downward pull is robbing you of energy continually.

The heat pumps best application is sustaining.

Davegvg

I'm south of you in CT and went through the same decision process...twice. Once when we built the pool several years ago, the other this past spring when I replaced the old heater.

I have a plaster pool, a somewhat dark gray. The pool by itself holds in the high 80s in the summer just from the daily sun exposure.

Since we use the heater primarily for the spa, and we wanted "instant" heat, we went with propane.

I installed a Raypack 2100 ASME heater this time around, it replaced a failed Pentair. Both were 400BTU heaters, propane due what was (and wasn't) available down here.

I just closed up my pool last week. I open it in late April and close it in late November. I swim every day that I'm home. We might heat the pool a handful of times a year, usually when the kids are having an early spring pool party or a late fall pool party. The spa gets used often.

I have a 375 gallon propane tank that gets filled roughly every other year.

I'll give a big thumbs up to the Raypack. It was so easy to plumb and wire up when installing, and it performed flawlessly.