Circulator recommendations

[barkeatr]

I will be installing a Empyer Pro 200 in early March...i have to run the water 140 feet and up about eight feet in an unpressuriezed system. My old Central Boiler that this unit is replacing had a hi lift circulator that did a fine job, but im replacing the boiler and circulator with this new system.

are there any recommendations on new technology or just any recommendations for circulators...are there any variable speed units or i see some that even sense temperature now.

thanks in advance

barkeatr

 

[heaterman]

I will be installing a Empyer Pro 200 in early March...i have to run the water 140 feet and up about eight feet in an unpressuriezed system. My old Central Boiler that this unit is replacing had a hi lift circulator that did a fine job, but im replacing the boiler and circulator with this new system.

are there any recommendations on new technology or just any recommendations for circulators...are there any variable speed units or i see some that even sense temperature now.

thanks in advance

barkeatr

What size tube and how many GPM do you need? Those are the two things that need to be pinned down in order to make an informed decision.

My motto: Don't just buy stuff, buy the right stuff.

 

[jebatty]

Under-sizing pipe and mis-matching circulator to the amount of BTU's needed to be moved ended up being the biggest mistakes I made on my original boiler install. A term like "high lift" are meaningless to me - it's all in the pump curve numbers. A mistake here is serious and expensive to correct, else you may have to live with an under-performing system.

I would start by determining how many BTU's you need to move to meet your heat demand or to move your boiler output, whichever is greater might be the best choice. Normal standard is 1" handles up to 80,000 BTU's and 8 gpm, 1.25" for 140,000 and 14 gpm, 1.5" for 220,000 and 22 gpm. This is based on delta-T=20, so if your delta-T is greater, pipe can be smaller, and vice versa. I would recommend not sizing smaller than this, though. Next calculate your pump head for the piping size you pick on the round trip to and from your boiler. Last, pick a circulator which in about the middle of its pump curve can supply the required gpm at the calculated pump head. In general, other things being equal, larger pipe = lower head = more circulator options.

 

[barkeatr]

thanks Jim...sounds good. high lift is a circulator designed to lift higher distances. My pipe is already installed. I assume I cannot go wrong by oversizing the circulator but I may be wrong, thanks for the figures and explanation.

 

[heaterman]

thanks Jim...sounds good. high lift is a circulator designed to lift higher distances. My pipe is already installed. I assume I cannot go wrong by oversizing the circulator but I may be wrong, thanks for the figures and explanation.

Oversizing a circ wastes energy and in a lot of cases will destroy it prematurely due to cavitation/suction boiling. Even in pressurized closed systems. You don't need a high head pump because of the elevation change because once the loop is full and air purged, the water coming back down cancels out the gravity factor of the water going up. In a case like that. make provision in your piping to purge the loop with a different pump or with a garden hose. Put an automatic air vent at the high point of the loop and you'll be all set.

Wilo S21, or Grundfos 15-58 will probably do nicely unless the tube in undersized for the amount of flow you need. It all depends on the temp drop you can achieve.
For example: We just installed a loop that measures just under 500' round trip. The little Wilo S21 is running on speed two and doing a measured 3gpm through dual 1" pex (2 supplies/2 returns) and that's all the guy needs because the heat emitters in his house will drop the temp about 35-40*.

One other thing. A "high lift" circulator is designed for loops with a high resistance to flow not gravity in the sense that you are pumping water uphill and leaving it there. A hydronic pump is called a circulator because it's a moving water in a loop.

 

[barkeatr]

thanks Jim this helps a lot. It may save me some money also!