Keep Trane Return Trap??

Mark_35

I am planning to replace my giant Ideal 1935 steam boiler with a nice new properly sized unit. System is original Trane two pipe with return trap over the boiler. Works fine since I replaced all the trap elements. Question, should I remove the return trap and two check valves and just use a gravity return or reinstall it on the new boiler with the two check valves. I have plenty of A dimension. I figure as long as I keep the pressure low, the gravity return should work and it seems like less hardware to go wrong.

Question 2 - should I keep the water line of the new boiler the same as the old, or can I drop it down lower? To keep it at the same level will require a lot of blocks below the new boiler. The wet return is at floor level from the far end of the house - no danger of draining any existing wet returns by dropping the boiler.

Unknown

Looking for trouble

An "A" dimension is the height the water will rise in a ONE PIPE SYSTEM, which has steam pressure pussing the water back into the boiler. A 2 pipe system with less than 28" of "B" dimension runs at a fraction of a pound of pressure. More pressure than that, and the returns will flood, and so will the boiler on shutdown.

Your two piper has no steam pressure pushing back.

Your system pressure has already been determined by the height of the piping above the boiler water line.

If you change the water line, make sure that you understand what that does to A) the steam pressure required, and B)the rest of the piping heights in the system.

You are on pretty thin ice with this plan. The Trane trap was there in case the coal fire built pressure beyond what the system was designed for. It pushed the water back into the boiler, because it had no way to stop the pressure from rising with a coal fire.

I bet you are using an electricly operated burner to replace the coal. The Trane trap is no longer is needed to control the pressure. Modern systems simply shut off the burner if the pressure (determined by the designer's piping choices) get's high enough.

You need someone with a better understanding of low pressure steam to look it over, before you start cutting pipe.

Noel

Steamhead

You have a Trane Vapor System

I agree with Noel, keep the Return Trap and try to keep the boiler's waterline as close to the old one as you can. Old Vapor systems were the Cadillac of heating, but you have to respect the principles on which they run.

Your new boiler should have a Vaporstat instead of a pressuretrol, so you can set the operating pressure at 8-10 ounces or so.

If the Return Trap needs repair, get in touch with Tunstall at www.tunstall-inc.com . They can repair or rebuild it.

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patrick linhardt

respectfully disagree

I agree with what Noel and steamhead are saying about the operation and identification of your system. However, with the inspection of a qualified contractor, I think your system can run just fine without the return trap and the two check valves. Have the contractor check that waterline, again under the right conditions it can be OK.
First, make sure the contractor sizes the new boiler by the installed radiation load and not the heat loss.
Second, make sure the contractor checks the "B" dimension, you need a lot for two pipe(That's why the return trap was used with the original coal boiler). If that's sufficient, go on and remove return trap. If not, repipe with it in system.
Third, like steamhead says, use a vaporstat to act as an operating control. And like Noel says, keep the pressuretrol to act as the safety device.
Fourth, have an additional pressure gauge added to the system that can read low pressure.
Fifth, make sure that old wet return is buried with water, but clean on the inside to easily pass the water back by gravity.
You sound like you know the basics of operation. But please have everything checked out. You can really get into some trouble and expense if not properly planned out.
Pat

Steamhead

Of course that system

can run without the return trap if you use a Vaporstat, but since it's there and apparently working, why not keep it as a backup? We all know about plugged pigtails.

Nothing wrong with wearing a belt and a pair of suspenders.....

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Unknown

I'm with Pat

The Trane trap will just be a decoration, once you control the pressure.

I might leave it in for the sheer beauty of the beast (check valves, too), but it won't hurt you if you don't rebuild it. The vaporstat (L 408A 1132) completely replaces it.

I also agree with all of the facts that Steamhead wrote.

Noel