Circulators or Zone Valves

Seattle Ron

Here is my first job with one circulator and four zone valves. I went to a Taco presentation the day before I started this mechanical room. I thought it made sense to use less power but make the one circulator work smarter.

System is working fine...but the house is still on the market...:>(

Iwanttobelieve

Circulators or Zone Valves

I'm looking to add a few more zones to my boiler to support an addition and an indirect hot water heater. Currently, my system has 3 circulators; 1 for the first floor, 1 for the second floor, and 1 for a bonus room. In my addition I'd like to have a new zone for the master suite, a zone for my work shop, possibly a zone for the laundry and common hallways(I may be able to tie this off the first floor zone), and a zone for the indirect. If I stay with using circulators, this would be 7 circulators which seems like a lot. Is using circulators the best option or should I consider going to zone valves? Also, any views on best circulators? Thanks.

Brad White_203

Zone Valves

I would make a qualified bet (not knowing anything specific about your house!) that any single one of your circulators would likely move enough water to heat your entire house.

That has been my experience on many, many "circulator-zoned" homes.

If each is the "Ubiquitous Taco 007", that could handle 100,000 BTU's per Hour against 7 feet of head or similar combination.

One way to find out, assuming your design is for a traditional and common 20 degree delta-T: Check your leaving temperature and returning temperature on any one zone. You may well find that none comes back more than five degrees, hey, even ten degrees cooler than it leaves. That means that you are moving two to four times the amount of water you need. Check it out.

Consider that each full-speed circulator will consume between 60 and 85 Watts- that adds up. There really is no need.

Each zone valve, when it closes, will impose a back-pressure on the circulator circuit, so a variable speed circulator would be my recommendation. Response mechanism in that case would be differential pressure but you could also use differential temperature which I have been specifying for about a year now and continue to do more often. That really allows low, low circulator speeds.

The "poor man's variable flow" system might use a differential pressure bypass relief valve as another means. As each valve closes, the water has to go somewhere so it bypasses the system and goes right back to the return side of the circulator.

Each zone valve gets to cast it's vote for it's own spaces' needs. A properly sized circulator, especially a variable speed one, will handle this range with ease.

I would still keep a circulator for DHW production however. Domestic Hot Water Production has no time for Democracy

Iwanttobelieve

Interesting

Very interesting idea... Any suggestions on controls that will take care of measuring the temp. and varying the speed?

Iwanttobelieve

Wilo Statos Eco 16F will do the job for most typical homes. At about $300, its maybe 30% more than a Star 16 + Differential Pressure Bypass valve from Danfoss.

http://www.patriot-supply.com/products/showitem.cfm/177273

I'm using this with 4 Honeywell Zone Valves on my 2000 Sq ft 2 story home.

John Barba_6

Another shameless commercial plug

Go to http://flopro.taco-hvac.com and click on the picture of the funny looking guy with Variable Speed Pumping next to his head. The video should give you something to chew on. The Taco 00-VDT has the Delta T control built in to the circulator and is programmed right out of the box to work with a 20 degree Delta T system.

Let me know if this helps...

Brent H.

Availability

The 008-VDT looks like an interesting option but both supply houses I've checked at don't have it or know anything about it. What is its availability?

Unknown

Another shameless commercial plug

???

singh

Knowing JB

he was talking about himself.

John, nice webinar, I found it useful. My take on it is having a delta t pump can increase not only fluid dynamics , but also can improve boiler efficiency, correct? Any clue on average by how much? How much wattage does the 008-vdt pump draw?
I'm just trying to factor in all the variables including cost and payback.




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Plumdog_2

Nice Job

Did your apprentice get his card filed yet?