Carrier RTU Heat Exchanger

[DesMech]

I have a customer with a large 20 ton rtu with a bad heat exchanger. I have done many of the smaller units and I call almost do those in my sleep, but this thing is completely different. It is a 48DJE024 Series 500AA. I am not sure what this thing is, but it is the biggest 20 ton rtu I have ever seen. I do mostly light commercial work so I have not run in to one of these yet. Anyway, I am trying to figure out how the heat exchanger comes out and how long it will take. Any advice would be appreciated. Thanks.

[DesMech]

43 views and no one has any input?

[baronpilot]

we have changed several and is one of the worse designs, are the burners tucked way back and very difficult to see. You have to tear the unit all apart to remove exchanger, be sure to caulk new one in w high temp rtv and try not to tear up too much insulation. Some units we have seen didnt burn correctly ie lots of sooting irregardless of burner or air adjsutments.

[vmc1161]

If I remember right we pulled the heat exchanger out the end opposite the gas valve , you have to open up the other end and the roof. It is fairly easy to do with two guys and some wood. Some of the screws may have to be cut and screwed in from the heat exchanger compartment. And we did crawl down into the condenser section. Check all the parts and gas valves and do it all at once if needed. Change the roll outs for sure, they go bad alot when there is a cracked H/E Also that thing will smoke like crazy so leave off the opposite end and put a section of plywood to divert the supply air out of the unit until the oils have burnt off. It took us about half a day each one, then testing and goofing around finished up the day. Hope this helps...call me if it will make you feel better, I wont answer but at least you will feel better...:D

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[y7turbo]

i just did both on a 48dje034 today, it was easy. im not sure how much different yours is going to be since the model # is almost the same, the one i was working was a 30 ton and your is a 20ton.

if it wasnt for some other problems, it would have been done in 6 hours for both hx's.

[DesMech]

If I remember right we pulled the heat exchanger out the end opposite the gas valve , you have to open up the other end and the roof. It is fairly easy to do with two guys and some wood. Some of the screws may have to be cut and screwed in from the heat exchanger compartment. And we did crawl down into the condenser section. Check all the parts and gas valves and do it all at once if needed. Change the roll outs for sure, they go bad alot when there is a cracked H/E Also that thing will smoke like crazy so leave off the opposite end and put a section of plywood to divert the supply air out of the unit until the oils have burnt off. It took us about half a day each one, then testing and goofing around finished up the day. Hope this helps...call me if it will make you feel better, I wont answer but at least you will feel better...:D

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Ahh, thats what I was afraid of. The ducts on this unit are out the side and the unit sits pretty close to a wall, so getting the heat exchanger out the opposite side of the gas valve isn't going to happen. I did pull off the top section over the burner compartment and I saw the screws were put in from the adjacent sections. :mad: What a dumb design. Oh well, Maybe I'll be able to get it out the top of the unit. Thanks for the replies guys.

Vmc, I might call you, but I won't be calling you anything good if this job goes bad.;)

Two guys with wood? I might pass on this job.:eek:

[DesMech]

i just did both on a 48dje034 today, it was easy. im not sure how much different yours is going to be since the model # is almost the same, the one i was working was a 30 ton and your is a 20ton.

if it wasnt for some other problems, it would have been done in 6 hours for both hx's.

Good deal. I don't think this unit has two heat exchangers, but I can barely see in there to tell.