Taco Flocheck Issues

Rizz861

Hello,

I was wondering if a Taco 221 Flocheck could be the source of a zone not heating. The basics: tstat good, circulator on and is also new but return isn’t coming back hot. All other Flochecks to other zones look good but this thing looks crusted as hell. If you look at it wrong it looks like it will start spraying. Pumps are on returns and Flochecks are on the supplies. What’s  interesting is when I try to fast purge the zone with all others isolated, the pressure climbs to the point where I have to stop because of the relief valve. I’ve never had this happen before. Usually I can throttle the fast purge to not blow the relief, but this zone I can’t. It’s almost like the check is stuck partially closed or something. I don’t believe there are any restrictions and this zone doesn’t have a run subject to freezing (we have had mild temperatures as of late anyways). Do these things ever fail partially closed? Also, the knob on the top, it’s my understanding it make it a check or bypasses it. If I go out CCW all the way, is it a check at that point? If I go in CW all the way, is it bypassed? This particular check looks like a turn with some channel locks could be a break. Any ideas?

hot_rod

It’s just a chunk of steel at the end of the stem. CCW should lift it up, or the flow from the circ

Remove the top, maybe it is stuck to the bottom somehow

EBEBRATT-Ed

Sounds like the fc is stuck. CCw should be open and CW normal operation.

Maybe a couple of gentel raps with a hammer will unstick it but it likely needs replacing

Rizz861

@EBEBRATT-Ed So when you say CW normal operation that is as in it is a check at that point and CCW open as in check is bypassed correct? So this was a job someone else was doing and got stuck on and they called me. I’d like to know in the future how to get it right the first time. So troubleshooting a bad tstat, circulator, or relay cube on taco controller is pretty straight forward. If I see this again, I would think the fact that I couldn’t bypass the water feed and fast purge without coming close to setting relief off would be a good indicator the Flocheck is stuck, would you say so too? My go to for checking pumps has been to check power at circulator and if return isn’t coming back hot it’s no good. This obviously puts a wrench in that. I’m thinking I should check amp draw for an accurate diagnosis from now on. Would this be the most accurate method?

EBEBRATT-Ed

What your doing is ok. The return should get hot if the system is not air bound and the pump is working.

As far as am draw goes it would be lower with a stuck flow check and go up when it's moving water but with small amp draw pumps it is hard to tell.

hot_rod

A voltmeter or a spin-d-cator is a good quick first step. Amp meter is next. But a stuck impeller will also show a current draw.
Some Grundfos and Wilo have a screw in the back that can be removed to observe the shaft spinning.

However it could still have a broken shaft at the impeller.

At some point you remove the bolts holding the motor into the body to confirm it spins freely when powered in your hand! Make sure nothing in the volute could cause it not to spin.

Usually if the pump motor is scalding hot the rotor is locked and you have an 80 watt heater😳

Joe Mattiello

You can replace the working parts of check valve.
sounds like it is stuck. Instructions are available at www.tacocomfort.com replace parts are listed too.
call Taco at 401-942-8000 for tech support 

EdTheHeaterMan

This is from a booklet I used to teach my seminars. It is the section of how FloCheck valves work. B&G called them Flow Control Valves. That is why there is a reference to "controlling flow"

Flo-Control™ Valves Control Overheating, Not the Flow!
Maybe “Flo-Control” was a bad name to give to this device back in the
old days when we were converting gravity hot-water systems to forced
circulation. The industry needed something that would stop the
hot water from rising up into the radiators when it wasn’t needed.
Hot water will do that, you know. It’s lighter than cold water.
But the name Flo-Control valve makes some guys think they can
balance a zoned system by turning the top levers on the valves.
That’s not what those levers are for.
Let’s take a look inside one of these things and make sure we
understand what its job is.
What we have inside is a brass weight that’s loosely connected to a
stem. The weight normally sits in the closed position and keeps the
lighter hot water from rising out of the boiler when the circulator’s off.
The circulator has no problem lifting this weight. As soon as it comes on,
the force of the water just slides the weight right up the stem and out it
goes to the radiators.
But then when the circulator shuts off, the weight inside the valve drops
back down onto the seat. It won’t allow hot water to rise out of the boiler
unless the circulator comes on again.
In other words, it keeps the zone radiation from overheating. That’s all.
The lever on top of the Flo-Control valve is there to give you a way to lift
the weight up off the seat should the circulator fail and you want to get
some temporary gravity circulation out to the zone.
You just crank the lever up; the stem rises and takes the weight with it.
But that’s all the lever does, it doesn’t control the flow. You can’t balance
the flow through the zones by turning those levers. That’s because
Flo-Control valves control overheating, not flow.
For the Flo-Control valve to function properly, the lever must be
installed in the top vertical position

spudtu

That is an excellent description, Ed. I've been trying to understand these valves and this is the first time I think I got it!

EBEBRATT-Ed

It is a weighted check valve that has provisions for manual opening.

spudtu

Ok, you guys gave me enough confidence to turn that little thumbscrew on my Taco Flochek valve (on the supply side). I'm pretty sure the circ pump on the return is shot, and I was just hoping for some convection flow so pipes don't freeze before I can get a new pump in there. But with boiler running, the supply pipe was barely lukewarm on the downstream side of the FC. And the thumbscrew was stuck/frozen even when I put pliers on it. I didn't want to force it and snap the stem or something. So I wirebrushed the visible threads, soaked it with WD-40 and waited a couple days. Went back this morning and put the pliers on it, turned strong but prayed, and it finally turned. And best of all, the pipes are good and hot all the way around back to the return side! Thanks for the education!

GW

I don’t see them sticking closed often; can’t even think of the last time- that’s a rare one. In wonder if oxygen is somehow getting into the system 

spudtu

Yeah, I wondered that, too. I thought maybe the pump was air-bound. It's quite possible, because I haven't ever been able to bleed the radiators - old coin bleeders that don't want to budge even with pliers, and I don't want to force them. But maybe I have more than one problem. The first time I fired up the heat this year, I got hot radiators. Then the next day I didn't.

The pump it has 120v when the tstat is calling for heat. I took the cartridge off the pump body, disconnected the power leads and put separate 120v on the pump wires. The impeller did not spin, even though it spins freely by hand. Also checked the capacitor while I had everything open. Put it all back together, ran the drain near the pump for a while, turned that FC thumbscrew, and started getting hot pipes downstream of the FC. If you say you hardly ever see a stuck FC, then I'm still wondering, too.

I also have another zone for the basement, and I think the pump went bad on that zone, too, last year. Radiator pipes burst in a poorly insulated spot. It was late in the winter and I never tracked down the problem. Funny thing is, yesterday I only turned the thumbscrew on the FC for the upstairs (the first zone) and then started getting hot pipes on the basement zone, too. Maybe draining that one drain valve got air out of both zones?

spudtu

Thinking this through again, is it possible the upstairs zone FC was not stuck, but simply not allowing convection flow in the pipes, as intended by design? If the pump is not running, then the FC would not allow convection flow because it would be closed. But now that I opened it manually, convection flow can happen, even without pump running?
Still doesn't explain why I'm getting convection flow in the basement zone when I was not before.

EBEBRATT-Ed

@spudtu

Flow checks were made to not allow water circulation unless the circulator is running. They prevent gravity flow. That is all they do, and they prevent water from reversing flow. They are a weighted check valve with a means of manual opening.

Most (maybe all) have some method of opening the flow check to allow gravity flow. Turning a screw, moving a lever etc. I have never seen a flow check get stuck closed. Having the screw, lever or opening mechanism rust up is fairly common in some designs.

hot_rod

Its would be unusual to get convection flow in radiators below the boiler in the basement 

Hot buoyant water goes up the cooler water drops

If the basement piping is below to top of the boiler that usually  as a thermal trap. You would need some forced circulation to get flow

spudtu

@hot_rod
That is a good point, thank you. The basement radiators are on the other side of the house from the boiler and down at basement floor level. Most of the piping to get over there and back is run at the basement ceiling (so above the boiler). But the piping drops down to floor level for the radiator section. That is the section where the radiator pipe burst last year. The basement floor is above grade in that area.