Indirect hw tank separate circ?

KevinCorr

An old boiler guy told me to put a circulator to any indirect when using zone valves for the other zones.

I have been using a 1" zone valve on the indirect and 3/4 on the other zones, plus the indirect is the shortest closest zone. I have had no problem with only one circulator for all the zones. (not counting radiant floors)?

CMadatMe

Is he the same

old guy that doesn't t use a zone control with priority? You should be fine with the zone valve providing your boiler circ (system circ)  is sized properly.

Jean-David Beyer

As usual, It Depends.

I have a W-M Ultra 3 boiler. The heat exchanger (the one with fire on one side, and water on the other) holds about 3 quarts of water and is made of aluminum. So they want serious water flow through the thing. It is primary-secondary piped, with a Taco 007 circulator in the primary loop. Whenever heating of the house is wanted, that primary circulator runs (and so does at least one circulator on the secondary side).



However they recommend connecting the indirect fired DWH across the supply and return pipes before anything gets to the closely spaced Ts. And when running that, you turn off that "boiler circulator" and run the one from the DWH. So it needs to be a Taco 007 as well.



You just gotta keep that water flowing through that heat exchanger when you could be burning 80,000 BTU/hr of gas in there.



But unless you have a boiler like mine, what's the difference if you get enough flow so the recovery rate is high enough?

PaulR

Mod Con Flow

Generally speaking, I will still use a dedicated DHW circ as my boiler has terminals for boiler, DHW, and system circulator.  It makes it easy on a DHW call in that the boiler pump will drop off and the DHW will assume priority.

I use Taco IFC circulators for my boiler pump and DHW pumps.

PaulR

Trying to attach PDF

The pdf I previously tried to upload, didn't.



I'll try it again. 



Are the bugs worked out on the new Wall, and is that preventing me from uploading pics at this time?



Paul

Jean-David Beyer

I use Taco IFC circulators for my boiler pump and DHW pumps.

For my boiler circulator, I use a regular Taco 007 because it came with the boiler and they said exactly where to put it. They even had it painted black. It goes in the return to the boiler from one of the closely spaced Ts. There is a FloCheck valve in the supply on the way to the other closely spaced T.



I have three other circulators; one for DHW, one for downstairs and one for upstairs. These three are Taco 007-IFCs. One was specified by the boiler maker (and the indirect fired DHW, made by the same boiler maker). The one for the downstairs (slab radiant) calculates out to need an 007-IFC, and my contractor used another one for the upstairs zone. There it is not so clear what I should use. I figured out a Taco- 008-IFC might be better to get the flow up a bit, (there are about 70 feet of 1/2 inch tubing buried inside the floor, 25 feet of 3/4 inch tubing and 28 feet of 3/4" Slant Fin). From a heating standpoint, this flow rate is fine, but from a "getting the bubbles downhill through 3/4" tubing, it is not quite enough ro get 2 feet per second through the 3/4" pipe.. I hope my Taco 49-125 separator will get them.

DanHolohan

You can upload pics,

but not PDF files. The folks at A.M.A. explained to me how these, when used on a bulletin board, can bring viruses into a site. I can load PDFs in the Library and you can link to them from if that works for you. Just e-mail them to me.

PaulR

Dedicated DHW Circ

Here is a zone valve system with a Taco 00 VDT driving the zone valves, an IFC circ for the boiler pump and an IFC for DHW.  With a lot of modcons now, the boiler pump will drop off when the (P2) DHW circ takes priority.



Click on the drawing to enlarge it.

Jean-David Beyer

Mine is pretty much like that...

except I have only two zones in addition to the DWH. And I use circulators instead of zone valves. Mine is done exactly as shown in the W-M Ultra-3 installation manual.



Your diagram and mine both have a minor fault that may not matter in the long run. That is that the air eliminator works only when heating of space is desired. Since my system was installed in late may, it was too hot to run those zones very much, But I do run the DHW all the time. So I never get much dissolved air out of the system. When it gets cold this fall, I will be able to run those circulators and get some air out of there (if there is any).

KevinCorr

thanks

Thanks for the input.



I simply use the circulator that is supplied with the boiler and then use Honeywell zone valves for all zones including the indirect tank.

I have not decided yet if there is any advantage to a circ instead of a zone valve on the indirect hw zone.



I have a Viessmann and a Buderus to install soon. My first one of each.

Jean-David Beyer

I have not decided yet if there is any advantage to a circ...

I, too, used the circulator that came with my W-M Ultra 3 boiler. Why waste it?



My contractor preferred circulators for zoning compared with zone valves. I could see a point to that at the time, but since then I figured out about primary|secondary piping the way W-M recommend it (boiler on primary, zones (except DHW) on secondary. And even they allow either a single circulator on the secondary loop and zone valves, or a circulator on each zone. I did not know there were constant pressure circulators and differential pressure bypass valves. By the time I found out about them, the system was already designed and I did not think the price of a circulator vs. the price of two zone valves and a dp bypass valve would be all that different, especially when there was the price of a new mod|con boiler, and indirect fired hot water heater, two convector transplants upstairs, labor, overhead, and profit for the contractor to be considered.



I do not know what my contractor pays for a Taco 007-IFC. I could get one for about $75 on the Internet, but I do not know what his wholesaler charges him or the markup he applies. I see the list price is about double that. And since I have mainly book knowledge of these things and no practical experience, I sure did not want to do the job myself. Buying the parts from the Internet and asking the contractor to install them for me seemed about as rude as bring my food to a restaurant and asking them to cook it for me.

hot_rod

how quickly

do you want to recover or generate the DHW?



With a single circ and a zone valve on the indirect you are limited by the Cv of the zone valve. Use a valve with a high Cv if you want to move a lot of flow. Generally 1 or 1-1/4 zone valves have a 7.5 Cv.



I used a dedicated circ on my system. With a Lochinvar 80K Knight I can run one hw shower @ 2.0 gpm faucet non stop and never run out of DHW, as the circ allows me to move all the boiler output to the large coil HeatFlo indirect.



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