creating zones inside a loop w/ 3-way valves

Ken_40

You've done the math properly. I incorrectly just assumed the Cv of a flow check (be it swing, flo, or spring) would be LESS than most ZV's, but you know the sizes and makes/styles involved, I don't.

The way it might be wired is to have the zone valve be the "trigger" for turning on the circulator, rather than the other way around. The end-switch on the zone valve is activated upon near full opening, then allowing something like an 832 relay then - turn on the circulator...



<A HREF="http://www.heatinghelp.com/getListed.cfm?id=504&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>

Mike C_6

load balance when modifying a loop -- keeping things even

Hi,

Thanks for this so great site !!

I was curious what your opinion was regarding the head-loss balancing in a modification project (for a loop with a non-permanently running circulator): could one replace a flow-check valve against siphoning with an electric zone valve (about 1/5 less friction/resistance), which would of course be explicitely driven open when the circulator runs ?

I'd be adding three other valves in the loop, and ideally I'd keep the load "as before". Thus no circulator change would be needed, no loop splitting, no new loops/circulators. Just a few bypasses in a few places, with their own thermostats, on their 3-way valves, and in parallel on the one brave circulator.

From my calculations, the new valves would drop the flow by 0.5gpm (each is 7Cv 3/4'') and thus stress the circulator. Our friend is a Taco007, already probably not far from its end of the curve -- I figure at least -8.6ft from the current system (280ft: pipes, fittings (equiv), check valve itself, 185F, 4gpm), without counting the boiler itself -- (how to get that?). Taco007 runs up to 11ft, they say.

True, there is no electronic speed control, so I guess anyway stuff has to be (re)sized for the appropriate flow rate, i.e. to be obtained from that intersection of system head-loss curve and circulator performance.

Basically the check valve seems to anyway have about -2.5ft head-loss, so a 8Cv 3/4 zone valve instead would only set me back for -.5ft. All in all new set back (three 3-way plus the 2-way regular zone) -2.8ft versus old (check valve) -2.5ft would seem a reasonable trade-off, with a very small drop in flow rate.

Again, if the whole idea has a chance to work.

I also may be overdoing the whole thing, since the flow-check must have been added long after the system was set in place, and perhaps without a significant drop in overall performance (actually to be seen -- 't'll be my first winter here). Meaning the system was maybe oversized to begin with ?...

Thanks once again !!!

M

Ken_40

Sounds like..

you're contemplating using a circulator and flow check and zone valve and using the bleed-pressure-value of the zone valve's spring release point as a flow restricter?

Is that what you ask our opinion of?



To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mike C_7

Re: Sounds like.. (check valve versus zone valve)

Thanks so much for the reply and sorry for the misunderstanding. I am rephrasing my question in a shorter and hopefully better way.

I am actually contemplating replacing the check valve with a zone valve. I hope two things:
1. to achieve the same effect (blocking syphoning in absence of circulator motion),
2. to have less of a head-loss (to thus compensate for additional valves to be inserted in the loop)

1. would be so by wiring the zone valve to open when the circulator is on and close otherwise (so I don't think it would have to do with bleeding, rather just "regular 'gate-like' functioning -- OPEN/CLOSE" behavior)

2. would be so because I think check valves are @2.5ft head-loss (about 83ft pipe length equivalent friction), while zone valves seem to be around 1/5 of that (Cv of 8).

The long story of the whole question is that adding other valves elsewhere might increase the total head-loss beyond what the circulator would like to see (from charts and formulae I came accross). My overall goal is to have things "as before" pressure-wise and flow-wise after adding those other valves. Maybe I am splitting peas ?... Downside is if this zone valve goes bad, there's no heat anywhere and the circulator might really be unhappy.

I hope this time I phrased it better --- thanks for all your kindness and time, any help greatly appreciated !!



M

Mike C_7

> You've done the math properly. I incorrectly

> just assumed the Cv of a flow check (be it swing,

> flo, or spring) would be LESS than most ZV's, but

> you know the sizes and makes/styles involved, I

> don't.

>

> The way it might be wired is to have

> the zone valve be the "trigger" for turning on

> the circulator, rather than the other way around.

> The end-switch on the zone valve is activated

> upon near full opening, then allowing something

> like an 832 relay then - turn on the

> circulator...

>

>

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 504&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_

Mike C_7

many thanks

Dear Ken,

Thanks so much for the kind reply !! I understand what you say about wiring, that's what I was thinking as well, happy to get that confirmed.



M