best quality/ efficiency check valves

[pybyr]

as noted in another post, I am interested in trying the Wilo circulators

the one really helpful Wilo NA tech that I did get through to, once, told me that they deliberately do not add check valves to their circulators, as, from an overall/ long-run pumping and wire-to-water efficiency perspective, having such a device in the volute or discharge really detracts from net efficiency... even though it's considered a marketing point/ bonus by other makershgawhat a

so...

if I go this direction (Wilo pumps) what are peoples' nominations for makes and models of check valves that will flow as well as possible, for as long as possible, with minimal head loss?

thanks

Trevor

 

[Nofossil]

Great question. I've had decent luck with the Taco and Grundfos integral valves, though I haven't been using them for long enough to really know, I've had not so great luck with swing type valves - the ones I have don't seem to be great at sealing consistently against reverse flow.

The spring type valves that I've used seem to create a lot of flow resistance compared to the integral valves in the circulators.

MHO, it's a cop-out for the circulator manufacturer to not offer check valves. Clearly check valves are going to be required in a decent percentage of installations, and they're in a great place to add a valve that's well matched to their circulator, at a relatively low cost.

I'd also be interested in any general experience as well as hard performance data. I've had a hard time getting specs on check valves. Sometimes you can get CV, but almost never opening pressure.

 

[pybyr]

MHO, it's a cop-out for the circulator manufacturer to not offer check valves. Clearly check valves are going to be required in a decent percentage of installations, and they're in a great place to add a valve that's well matched to their circulator, at a relatively low cost.

here was the rationale from the guy I spoke with, a week or so ago, in the tech dept at Wilo Canada, who generally seemed to know his stuff

he said that having the valve in or very close to the pump, either immediately upstream or immediately downstream of the impeller, in the areas where there's always, unavoidably, a lot of turbulent flow, adds a lot of resistance and lowers overall pumping efficiency signficantly, as compared to putting a check about 8-10 pipe diameters away, where the fluid flow is smooth

sorta rang true with things I've read from Siegenthaler about fitting distances

since Wilo does nothing but pumps, and is, I think, the single biggest pump mfgr in the world, and is way out on the cutting edge with some of their smart ECM products, I tend to give their explanation more than if this were just someone from "joe's pump co" that were trying to sell me the same explanation for omitting built-in checks.

still scratching my head, a bit, also, about just how badly or where I will need checks in my intended layout; hoping that the Twin Tees, leading to ZERO differential across the secondaries, will tend to discourage ghost flows some on their own

any input from the "pros?"

thanks

 

[Couderay80]

Put the check valve a few pipe diameters away from the pump discharge. I usually use a 6" nipple or longer after the pump and have had no problems. Swing type on horizontal piping and a spring style in vertical piping. If you are really worried about the check being restrictive go up one size on the valve itself.

 

[steam man]

I would think the check valve would have the same resistance whether turbulent or laminar flow. However, the check valve may cause some increase in turbulent flow thereby increasing resistance. My only thought is that if it "significantly increases resistance", why hasn't the other pump mfg done away with them. My Grundfos 3 speed pump shows the curve with and without the check valve installed. For the most part the flow difference looks very minimal at flow rates below 10 gpm. Above that up to 25 gpm the difference is probably 1 gpm diffference. I would argue that even a check valve installed downstream of the pump will cause that difference, maybe more.

Seems like the the internal flow check should be fine.

Mike

 

[mtfallsmikey]

Fired my boiler for the first time this weekend, had ghost flow to both coils...posted this question on heatinghelp.com as well....how about using a B&G;flow control valve? both of my coils/circ. combos are piped P/S.

 

[deerefanatic]

I have no flow checks and I do get a ghost flow to my water-air HX in the furnace. Funny thing is, it is situated BELOW my primary loop in the boiler shed, which is slightly uphill form the house and above ground whereas my furnace HX is in the basement of the house.. Oh well. It isn't much.. And the blower kicks on and sucks the heat out so it's not wasted........ Kinda strange though.

Either way, I think it's true that flo-checks in the pump probably are a _little_ more restrictive than down pipe, but not enough to make it worth the potential leaks from an extra set of pipe fittings......

 

[deerefanatic]

As for brands of Circs, I stick with Taco for everything except for the 15-58 3 speed grundfos as Taco has nothing quite like it..... I like taco for the fact that they have really good information on all their products and they are priced extremely competitively, and are domestic.

 

[in hot water]

1/2 psi pop pressure is what I have been told. Really not enough pressure drop to be concerned with. they did increase the bore diameter from the first version in the Grundfos brand. Some pump curves show the curve with and without the check installed.

hr

 

[Nofossil]

1/2 psi pop pressure is what I have been told. Really not enough pressure drop to be concerned with. they did increase the bore diameter from the first version in the Grundfos brand. Some pump curves show the curve with and without the check installed.

hr

I'm missing the reference here. I'd love to find a check valve with at 1/2 psi 'pop' pressure. Do you have a brand / model reference, or are you referring to the Grundfos integral valve?

1/2 psi should be enough to stop ghost flow in most situations, I'd think.