quick question

Paul S_3

im installing (2) Williamson gwa 50's with an output of 38k.. for each apartment....heat loss is about 33k at 0F....i would like to protect boilers with a 1/2 line in front of pump to return with globe valve in line.....what woukd you guys do "real world" BPvalve isnt in budget either is iseries....thanks Paul S

hot_rod

What type of heat emitters. It's rare to need protection with fin tube or any low mass types. Cast iron rads?

The only absolute means of providing return protection is with a devise that can detect and respond to temperature. Bypass valves or pumps, they just guess

Paul S_3

one system CI bsbd...other CI rads

hot_rod

Heat emitters already installed? If the emitters can dissipate the heat energy faster that the boiler provides it, you have the potential to run below dew point.

The thermal mass and volume of system fluid would factor in also.

The two ball valve balance method is only good for the single condition you set it for, above or beyond either it doesn't protect, or bypasses more than needed.

There is always the "poor mans method"

Some of the basic Viessmann cast iron boilers had an additional aqustat that turned off the pump when the boiler dropped into the low return temperature conditions. A simple, somewhat crude, bang-bang method of protection.