Twin Steam Boilers with hot water takeoffs

Mark_35

We are replacing twin steam boilers that have hot water takeoffs (bottom taps front and back) feeding heat echangers for hydronic loops (400 MBH each).  Don't have a lot of time to re-arrange the whole system so we are trying to work with what is there as much as possible.  The old boilers were gravity return, but the water volume of the new boilers is insufficient for gravity return so we are putting in twin feedwater pumps. 

First question:  Is the hot water connection between the boilers likely to disturb the water line in the idle boiler.  Will the steam in the header drop the line in the idle boiler? 

Second question:  Will it drop it enough to call the feedpump on the idle boiler?

We were considering adding a lockout on the feed pumps to shut off if the boiler is not enabled.

Dave in QCA

Questions....

What pressure is the system operating at?  The lower the better, you don't want to inadvertantly raise the pressure becuase this will cause lots of problems.

Can't you find a boiler that has a higher water volume?  The additional cost would probably be more than saved by eliminating the feed pump system.  Not only is there the issue of initial cost, but upkeep and maintenance over the course of the life of the system is a factor too.  Keeping it simple could save a lot of money!

Dave in QCA

What Size are the Boilers?

What size are the boilers?  Please specify whether the rating is input, gross output, net steam BTU, or  steam sq ft.