Still need advice from real experts...

Jamie Hall

I have designed a revision to a vapour steam system, and have two contractors working on it. One says my concept will work, the other says I am bats and proposes something quite different. I need your opinions and reasons...

The application has two quite distinct zones (with existing radiation and piping in each): one is to be maintained at 'normal' room temperature, and the other at about 40F (except now and then, for only a few days at a time). There is an existing Peerless boiler which feeds, quite adequately, the 'normal' room temperature system. No problem so far. The other system is valved off, at the present time, with a single large gate valve on the steam main (no other valves). My proposal is to add another, smaller, boiler (keep the water levels the same, second Hartford, etc.) piped to the same main header (an old header from a H.B. Smith boiler, long since gone) (about 30" up from the top of the existing boiler, never mind the water line -- nice steam!) sized to handle the additional load from the 'other' system (based on equivalent radiation, allowance for pickup and so on). This boiler will also be controlled by a Vapostat, but set slightly higher than the existing one so the new boiler runs by preference (since it is more efficient). The 'other' zone would be turned on or off by motorizing the gate valve splitting the two sections, and controlling that valve with a low temperature thermostat in the 'low temperature' zone.

One contractor says that's a little unusual, but why not?

The other contractor says that a) you can't possibly run two boilers together into the same header; b) even if you could, they would have to be identical (which would mean two new boilers, both drastically oversize for the existing heated area) and; c) you can't control the heating in one section of the system with a single main valve on that section, you have to go around and turn all the radiators on or off by hand (about 16 of them!) when you want to vary the temperature in the 'other' section.

I fail to see the difference between turning all of the radiators on and off by hand with individual valves and turning them on and off automatically with a single valve, and the contractor can't explain why a single valve won't work.

I distinctly recall seeing ways to hook two boilers together into one steam main in The Book, and the contractor can't explain why it can't possible work.

I fail to see why two boilers of different ratings can't be used together (assuming equal water levels), and the contractor can't explain why they won't.

HELP!

Thanks-- Jamie Hall

Frank_5

yes you can............

tie in two boilers into a common header, but there is a lot of work to do. Basically what you are doing is a lead-lag system. Works like this: Each boiler to have it's own individual header and equalizer; the steam take off from each boiler to be fed into another header. (Use a steam trap at the lowest end)Then into the zone valves. Returns to go to a boiler feed tank w/ separate pumps for each boiler. No common return tie in at boilers. Feed directly into bottom of equalizer, not into Hart. Loop. Install steam traps into equalizer about 2" above water line of each boiler. Dump them into feed tank.

Unknown

Jamie, yes you can do that.

There are more than one way.

The second contractor sounds like he tried this once, and ran into problems. I don't think he tried to solve the problems.

The two boilers can be different sizes. By using vaporstats to stage them, you can choose and change which leads and which lags. That itself is a good reason to do it that way.

I have had luck doing this with pump tanks, and without, using a common return and a common header.

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Noel