cast iron vs. plastic headers in heater, digital vs. non-digital

Hi,

we are replacing our pool heater this year. I have found this heater that looks pretty good for the price:
Raypak Millivolt 399,000 BTU Propane Gas Pool Heater - 0-2,000' Elevation - P-R406A-MP-C

from this company:
http://www.poolsupplyworld.com/pools...cts/009203.htm

we have a new pool guy that so far we like more than our last. We live in the northeast and he has suggested 1) this is a good price for this heater 2) we'd be better served with a heater that offers cast iron rather than plastic headers and 3) stay away from digital units due to the high price of repair (our last heater was ruined by mice nesting in the heater in the winter).

any thoughts on his assertions? Would also be interested in any other suggestions or specific heater recommendations.

actually, here's one for $500 more that has glass lined cast iron headers:
http://www.poolsupplyworld.com/pools...cts/009247.htm

worth the price difference? Perhaps the difference in repair cost and efficiency would pay for the higher price?

best,

My experience with pool heaters, while much greater than that of the average pool owner, is not on a par with a residential service guy. However, I also have experience on similar systems in a prior life as a commercial repair plumber. So, with that in mind, here are my observations:

1. I hate millivolt systems with a passion. I've worked on them in old gas floor furnaces, in commercial gas water heaters, and on pool heaters. They are powered by the tiny amount of electricity that can be generated by a bundle of thermocouples (called a thermopile) that is heated by the pilot flame on the heater. They are hard to light, because the system won't operate till the thermopile is hot. And they are EXTREMELY sensitive to any corrosion on ANY one of dozens of electical connections. Given that around pools you always have (a) moisture, and (b) chemicals, you almost always have (c) at least a little corrosion. You want to talk about repair costs: consider paying a knowledgeable pool service guy $80 per hour to check every stinking connection till he finds the one with high resistance that is causing your heater to balk. Worse, consider paying a not-knowledgeable service guy $40 per hour to NOT find the problem.

Pool dummies can replace electronic modules.

Ask your pool guy what the maximum acceptable resistance is on a millivolt heater circuit. If he gives you and answer in the single digit ohms (say, 4 ohms), you can consider a millivolt system. If he says, "Huh?", forget about the millivolt systems.

Personally, I would never even consider a millivolt system, except in locations where it was impossible to provide the electrical feed required by either a standard heater or an electronic one.

2. Glass lining sounds better than it is. Chattanooga was home to one of the original makers of glass-lined steel water heaters, WL Jackson (now out of business). TN-AM water company in Chattanooga delivered soft low pH water (~7.1 at 50 ppm CA) to homes in Chattanooga. Copper water heaters (yes, there were once solid copper water heaters) lasted as long as you could keep the wiring and elements replaced. Glass lined steel heaters lasted 7 - 11 years, max. Pool water is MUCH more corrosive than that tap water. And, I doubt that the glass lining process done by the pool heater maker is as effectively applied as it was in those water heaters.

3. If you think there is EVER a chance of installing a SWCG on your pool (salt chlorination) you should consider a heater with a cupro-nickel heat exchanger and plastic (or if anyone makes them, cupro-nickel) headers.



Others may have other observations. But those are mine.

Ben

thanks Ben! Sorry to ask newbie questions:

- so there are three types of heaters, millivolt, standard and electronic?
- I don't think the heater in question is glass lined, just the headers. My basic question is are cast iron headers better than plastic headers in the northeast?

tia,