I would go with a 30k BTU vent less blue flame type with a thermostat and oxygen depletion sensor. Most GHs are not sealed enough to require a separate fresh air supply. If you take extra steps to seal and insulate the GH, all you need for fresh air is to leave the vent cracked a little. I would also install a carbon monoxide detector, just in case. John

Sorry if this is a bit long . . . Due to frequent power outages where we live, a few years ago I installed a Myson 325 propane tankless water heater in parallel with the electric tank that normally provides our house with hot water. As a back-up system it has been great though it has some quirks that would cause me to not want it as my primary source of heated water. Anyway, my main problem with it is the external pressure relief valve will start to flow if a hot water tap in the house is only opened just far enough to cause the burner to come on. Obviously the water in the coils is getting too hot under this circumstance (low demand) causing the excess pressure. To compound this problem, when the house tap is then turned off the flow at the pressure relief valve is now great enough to cause the burner to remain lit as the system thinks that a tap is still open somewhere. I have played around with adjusting the water flow metering valve and the gas thermostat adjustment screw but can't seem to find any settings that solve this problem. I thought the thermostat adjustment would adjust the burner but after tweaking it up and down I couldn't really tell what, if any, changes it was making to the system. The only way that I can get the pressure relief valve to stop flowing (other than turning off the gas to kill the burner) is to fully open a hot water tap at a garage sink near the heater thus greatly increasing the flow which cools the coils down significantly. Then by abruptly shutting the tap off the burner will shut down. So, I'm wondering what the solution to this problem is. Would an expansion tank on the hot water side help matters? Do I need a technician? The owners manual isn't the greatest and of couse in the trouble shooting chapter there is no mention of this type of problem. Advice anyone? Thanks in advance!

It is likely air in the line leading from main to heater. I suggest haveing the propane company send someone back out because their service call is much cheaper than a plumber's. Relighting it yourself based on instructions gleaned on the net is not a good idea. . Time for a story about tinkering with propane gas. Man jumped out of a plane for his first parachute jump. Unfortunatly he wasn't paying attention when given instructions earlier about operating his chute. Just as he was giving up hope,he sees another man flying up toward him from the ground. As they passed he shouts "hey do you know how to open a parachute? "No,comes the reply,do you know how to light the pilot on a propane water heater?"

So a heat pump won't get the spa up to the mid 90's if I just adjust the lines so that most of the water is going into the spa? Like for the most part the spa is used for younger kids to play in and not like an adult "spa" where you might have the temp up over 100. Generally the way I use the heater is to heat up the pool to the low to mid 80s. Then adjust the lines so that most of the water goes into the spa and that heats up hotter and then the spillover gradually keeps the pool warm. I guess I am trying to save money on the propane cause they have me trapped. But if a heat pump won't realistically do what I need it to do I don't want to spend all that money on it. Thanks for the input!