My gas heater in the past has work quite well. I just hooked it up to a 'new to me' spa and after about 1 hour I got barely warm. In the past In 1 hour I could boil a ham. I thinking the manifold maybe plugged up. I ideas on the best way to clean out the manifold or plumbing of a gas heater. Yes it is working the burners are lit and hot.

Thanks for the help.

Glenn

Could this new spa be larger than the last?

Yes it is a little bigger, but I don't k that is the problem. I thinking a Mud Dauber Wasp made it home inside the plumbing. The heater was left sitting for about 1 year with all the plumbing wide open. Bees love to find little places like that for there home. I getting quite a bit of sand and dirt in it for no reason. Nobody has gotten in it yet. I vacuumed it out last night and the sand and dirt is back today. I leave the pump running for many hour during the day to get the love bugs out and make sure nothing is leaking. Its mating season in Texas for love bugs. My car is covered in dead bugs.

Thanks,

Glenn

Brand, model and btu rating of heater? Any idea how many gallons the spa holds?

The heater is a Comfort Zone, input btu 150,000 and the output is 105,000. Model number CGRV-150N/HT-P (if my wife read it right).
I have no Idea how much water it holds. Its average size 5 seats and one louge. The heater is pretty beat up, I thinking about getting a new one but I need to get a cover for the spa first. I have 2 kids and one on the way.

Thanks

Glenn

Size wise that heater will heat 500 gallons of water about 25 degrees per hour. That's all. If you start at 60 degrees, warm is all you'll get after an hour.

I'm not familiar enough with the brand to advise on repairs, sorry.