Delayed condensate returns

109A_5

@ted_p I think the float @bayridge is referring to adds municipal water to the system when the tank is too low to keep the water level above the pump intake. The pump is controlled by the boiler's LWCO system. The system with a newer boiler may not have enough water when steam needs completely fill the system. Also the system is big enough that it takes time for the condensate to start returning.

If the boiler's water capacity is too small the you need the extra water to keep the boiler running to fill the system, otherwise the boiler will shut down on low water and have to wait for the condensate to return.

Waiting is not good when you are trying to heat a building in the cold.

So the extra needed water capacity is external to the boiler. An oversized tank may not bother anything (except the cost) if the control system is set up correctly.

ted_p

@109A_5 : You could easily be right. Taking a second look, I do see where he says "The boiler feed tank is connected to the boiler's low water cut off", which clearly suggests a feed unit.

But other things that @bayridge said still make me wonder. A 38 gallon feed unit is awfully small for a boiler designed to steam at about 7 gallons/minute. That's not even enough to give you 20 minutes operation with a 35hp boiler. He's sure the tank isn't overflowing, which is what an undersized feed unit would do when the condensate finally makes its way back from the building; a condensate pump, on the other hand, regardless of receiver size just kicks the water back to the boiler as fast as it fills. He says "The auto water feeder is connected to a water meter for measuring city water added. Pre-boiler feed tank installation we were adding 120-130 gallons a day or 12-18 gallons per cycle as soon as we added the feed tank we have reduced the amount of water added to 2-3 gallons per cycle" which sounds to me like the this water feeder was, and still probably is, on the boiler itself.

I agree that there's no harm in having an oversized tank if it's a boiler feed unit, but not if it's a condensate pump.

It'll be interesting to see what @bayridge says when he replies.

dabrakeman

https://forum.heatinghelp.com/discussion/comment/1852120#Comment_1852120

https://forum.heatinghelp.com/discussion/comment/1852120#Comment_1852120

Is there indeed some kind of open overflow drain from the receiver tank??