Does baseboard loop from condensate return add to boiler BTU

Joseph_4

I have a customer who has a two hundred thousand BTU boiler.They have about 50 to 70 thousand that they need for two baseboard loops I want to add an everhot tankless unit to accomplish this. Does it subtract from the boilers BTUs thanks Joseph HHI services

Jamie Hall

This is steam, I presume? What is the EDR load of the system without the baseboard units? What is the EDR rating of the boiler (sorry, but "two hundred thousand BTU boiler" just isn't useful information -- is that gross input? Net output?).

If the EDR load of the system and the EDR rating of the boiler are similar, or if the boiler is oversized, then you should have no problem with the baseboard loops. They don't feed off the condensate line, though -- they come off the boiler itself below the water line. They can return to the condensate line.

EBEBRATT-Ed

No.

But the hot water load should not exceed the piping & pickup load for the boiler which is 33% of the boiler output

Joseph_4

Ed Im curious to understand is this special specifically to steam or would it be true by forced hot water if I'm using a 15 percent pickup factor also if they removed some of the steam radiators so that this boiler is oversized then I'm assuming I would have even more BTU available for hot water loop is that correct 

EBEBRATT-Ed

This only applies to steam,

Lets say a steam boiler has a net rating of 833 EDR/sq ft of steam radiation or about 200,000 BTUs
which is 833 x 240 btus/square foot 833 x 240=199,920

200,000 x 1.33 piping and pickup=266,000 so that leaves you 66,000 you can use for the hot water load maximum

Assuming the boiler is 80% efficient (266,000 /.80)=332,500 would be the boiler input.

Their are some other losses like heat lost through the jackett but the above is pretty close


So in the above example, 332,500 is input, 266,000 is gross output, 66,000 is the pick up load used to preheat piping and 200,000 would be the amount of radiation that can be connected

So a steam boiler is "oversized" by the PU factor of 1.33. The .33 can be used for a HW loop but if you use more than that the boiler may not be able to heat the connected load.