I have a Raypak 400k ASME heater. Propane. It is not a Nox model. Copper HX. I tried to buy it local but the local Raypak reseller refused to order me an ASME heater, saying I didn't need it. Well, that might be true. But I wanted it. lol.

Because of the troubles I had with the old Pentair, I wanted something a little more durable, and maybe a little bit better built, even if durable in this case was in the eye of the purchaser (me) and not anything tangible. So I ordered it online and swapped it out myself. Paid roughly $1800. Installation was pretty easy to do.

It replaced a Pentair minimax 400k unit that was nothing but trouble.

I've had the Raypak in now for several years. Maybe five? Pretty user friendly regarding maintenance, all I've really had to do is winterize it and then open it up in the spring. Haven't had to replace any parts.

I'm in CT, my season goes from April through November. Pool is 20' by 40', about 20k gallons, liquid chlorine, and I have a Pentair Quad DE filter and a Pentair VS pump. I installed the Quad DE last year and the VS pump this year. I'm thrilled with the pump (saves big money over my old single speed pump).

The filter is great, I got the Quad DE 100, which is "oversized" for my pool. But I don't have to clean it at all during the swimming season. Only when I close the pool down in the fall.

I use the heater more for the side spa than for the pool.

I would tend to agree with mongoct. As far as durability is concerned Raypak is the way to go. They do have two different types one being for the "residential" and the other being for "commercial" pools. The ASME version as stated above is the latter. They look almost identical with the only differences being the headers (ASME version has cast iron headers and the non-ASME has Capron plastic headers), and the heat exchanger inside the unit itself is 50% thicker copper on the ASME version.

The durability is definitely higher on the Raypak ASME model versus the other non-ASME heaters out there. Pentair, Hayward, and Jandy all have ASME versions of their heaters, however, if you're going to spend the money on a ASME heater I would say go Raypak.

Hope this helps!

Thanks for the feedback. We visited the pool store over the weekend to learn more about heaters. I don't think we need the NOX heater, since we don't live in Texas or California. I'm not sure if we will get the ASME or the standard heater, copper or cupro nickel heat exchanger. Does anyone have an opinion about copper vs cupro nickel?

I would agree Raypak makes one of the most durable heaters. I had one for 15 years and just replaced it a few years ago. I would recommend you at least get the ASME version of the heater for the small price difference.

I have cupro- nickel. I felt it was worth the price difference. But it all depends on your water chemistry and hardness.

If you take care of your water then Cu should be fine. I have Cu. If you're sloppier about water chemistry, if your maintenance is intermittent, if you have kids peeing in the pool or perspiring adults in the hot tub every night and you're always chasing balanced water, then cupro nickel could give you better performance.

But I also use 12% liquid chlorine to chlorinate my pool.

If you have a SWG, or are considering instaling one in the future, SWGs can up the total dissolved solids in the pool. When you have high TDS water coursing through the heat exchanger at high flow rates, it can erode the Copper.

Cupro-nickel could be worth going with if you have a SWG or if your have difficult water chemistry.