Cleaning heat exchanger internally...

[DennisP]

Hey guys, putting a heater into service, the whole heater is new except for the heat exchanger.

I was thinking about cleaning the heat exchanger with something like vinegar or lime-away/CLR???

Basically noticed a little scale buildup when I pulled the drain plugs. I just want to make sure it is clean and that I don't have to mess with it much for at least a few years outside of winterizing and cleaning it up in spring.

I mean, I *can* take the heat exchanger apart and clean it out that way, but then I would be better off putting in new header seals... I figure cleaning it fully assembled would not only be easier, but potentially quicker overall.

Any suggestions on the best cleaning method?

I am in no rush to get it done overnight, so I have no problem with filling it with a cleaning solution and letting it sit for a few days.

It is a Jandy/Laars LG250P (converting it to NG) for reference.

 

[DennisP]

Wow... No responses?

Oh, I converted the heater just fine. Used a .09375" (3/32") drill bit to drill out all the orifices, and reamed the pilot hole with a needle. The "factory" orifices were size 43, which comes out to a .0890" hole. I went with a orifice 42 size which was close enough to a 3/32" drill bit to make things easy. I drilled the orifices from the inside out and deburred the outer hole on each. I also put in a 391936 Honeywell conversion kit to change the regulator on the valve for NG. I figure the original pilot orifice was about a .008-.010" hole size and read that for a NG pilot with thermopile you want at least a .018", so I used a corsage needle to ream the hole to between .018-.020" size. I figure I can use the pilot adjustment on the gas valve to adjust it properly, but it is at least within adjustment range now. For final tuning I can adjust the regulator slightly down from 3.5" WC to have the size 42 orifices put out as much as the size 43 at 3.5" WC.

And I found out a 1.5" pipe coupler is the perfect size to fit inside the in/out manfiold header to hold the rubber gaskets centered. I laughed at the $140+ they wanted for a pair of flanges and gaskets. I got a hold of a pair of 2" floor flanges, cut them into diamond shapes, drilled the bolt holes on the ears. Cost of the flanges, $15. I then found a set of rubber gaskets with an inner lip for $1.25 each. They fit and locate themselves in the new flanges and are thick enough to seal really well. Now that I have figured out an inner support I will just buy a CPVC coupler for $3, cut it in half, use one in each manifold hole, put the gaskets on and then I spent $5 on stainless socket cap bolts and washers to finish them off. With a couple of 2" CPVC nipples I think the total cost will be $30 or so, and the bonus is I can replace any part with stuff I can get locally instead of needing to order things online. I already have 2 extra sets of flange gaskets and will be using anti-seize on the bolts to make future servicing a non-issue. Oh, I also painted the flanges with high-temp engine enamel so they should remain serviceable (and look good) for many years. I also will be painting the headers on the heat exchanger as well to protect them too.

All in all I have about $110 into everything needed for this heater (including the aforementioned flanges/gaskets, natural gas conversion and black pipe/fittings and ball valve to plumb it into the gas line). Grand total cost, lets just round it to $400 for all, including the heater. Not bad for a 250k BTU unit. And, again it was such a deal since all of it was brand new (manufactured date of 11/03) with only the heat exchanger having been used for a season and a half.

If no-one else replies I will post back with my results of the heat exchanger cleaning myself.