adding steam radiators to an addition

joseph gove

customer of mine wants to know whether i can add 3 steam radiators to his addition. new boiler has plenty of juice to spare. problem is, the new radiators are 40' from the boiler. what do i do? should i run a new main line straight off the boiler header with return & all? or do i continue the end of the existing main another 15'? do i have to multi air vent the line (whichever it is) in order to get all the new radiators in sinc with the old ones? and won't that release the dogs of war on the system? thanks for any & all responses. danny, would you try this one yourself? again thanks for the help.

Brad White

In theory

I would go back to the main header at the boiler. This way you get the same "starting torque" as all of the other branches. Size that branch as if it is the only one the boiler sees.

In other words, size it for the connected radiation and distance (not that it is much) and vent it accordingly.

If you were to extend an existing branch, even if apparently capable of handling the additional load, it could still affect what you know about that branch's performance. In other words, if it works now, do not mess with that branch. Low pressure systems mean any minute pressure change is magnified as a percentage of the whole.

If the returns are wet returns and properly sized, I would extend and connect to them. Wet returns are more forgiving and besides, if you are low, they all see the same head imposed on them.

In actual practice and the tricks it might entail to extend, offset around any obstacles and so-forth, I will leave that to Steamhead and other more knowledgeable day-to-day practitioners.

My $0.02

Brad