Possibly cut the valve out on the other 2 legs far enough away so as not to damage pipe dope when you reassemble with sweat couplings after leaking leg fix. If you didn't want to consider re sweating legs or can't cut the 2 legs far enough from the valve, I'd consider shark bites
Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime
- Thread starter velvetfoot
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maple1
Minister of Fire
I have unions in my system in strategic (I think) places, made putting some things together easier & hopefully anything I will have to do in the future easier too.
I also have had issues getting them to not leak. So I got a tube of some siliconey type stuff, that I found in the automotive section of the local Canadian Tire store, that is meant for sealing things like carb bowls. Actually, I guess I already had it here from doing some work on bike carbs. I forget what it's called, I think something 'moto' related, but it stays soft & flexible & is meant to allow easy disassembly. I just put a little thin skin coat of it on the union sealing surfaces, then tighten. Never had one drip from them after using it, and I did end up taking some of the apart & reassembling in a couple places to do other things later with no issues.
EDIT: Just ran down stairs & checked - it's Permatex MotoSeal 1, has a pic of a MX bike on the package.
I also have had issues getting them to not leak. So I got a tube of some siliconey type stuff, that I found in the automotive section of the local Canadian Tire store, that is meant for sealing things like carb bowls. Actually, I guess I already had it here from doing some work on bike carbs. I forget what it's called, I think something 'moto' related, but it stays soft & flexible & is meant to allow easy disassembly. I just put a little thin skin coat of it on the union sealing surfaces, then tighten. Never had one drip from them after using it, and I did end up taking some of the apart & reassembling in a couple places to do other things later with no issues.
EDIT: Just ran down stairs & checked - it's Permatex MotoSeal 1, has a pic of a MX bike on the package.
Possibly cut the valve out on the other 2 legs far enough away so as not to damage pipe dope when you reassemble with sweat couplings after leaking leg fix. If you didn't want to consider re sweating legs or can't cut the 2 legs far enough from the valve, I'd consider shark bites
Seems to be holding after heatup on oil
Didn't get a good fill. Control not that good. Have to fool around with settings. I wish I knew what I was doing there. Might try relocating the sensor. I'm hoping the high cv of the valve isn't a factor, as Bob indicated in another thread.
Didn't get a good fill. Control not that good. Have to fool around with settings. I wish I knew what I was doing there. Might try relocating the sensor. I'm hoping the high cv of the valve isn't a factor, as Bob indicated in another thread.
That's good to know, alas, the controller is by Honeywell.
setpoint, Throttling range, proportional, integral, derivative...ai yai yai.
I relocated the sensor right after the valve outlet and it works like a charm, even with default setting of 400 seconds for Integral, 20 F for throttling range and 0 for derivative.
Alas, now the boiler pump is heating up the two zones without the zone pumps being on, pumping through the zone pumps and the swing checks. I turned it down and the boiler temp went up and it turned off. I can't win for trying.
Alas, now the boiler pump is heating up the two zones without the zone pumps being on, pumping through the zone pumps and the swing checks. I turned it down and the boiler temp went up and it turned off. I can't win for trying.
I wonder if I could replace the zone Taco flo check valves, which go to each zone, with zone valves? They wouldn't be needed with the zone valves in place, no?
The basis of my system is a typical old school layout where the zone pumps pump to return. The boiler pump I added also pumps to return.
I'll run it some more (on oil). I am running it now with bypass closed and so far it seems to be running as it was, knock on wood.
I will have to use what Honeywell calls the "digital input", which will send the valve to 0% (bypass) upon a signal, which will have to be when the oil boiler is off and the heat is coming from the tank. That is, the flow changes direction and the mixing valve has to be open to the tank when extracting heat from it.
If my current no-bypass run looks okay, next time I'll try it with the mixing valve "in the mix". Perhaps the constant seeking previously (before I learned the secret) had something to do with it. Or, it's flow resistance of the valve or something.
The basis of my system is a typical old school layout where the zone pumps pump to return. The boiler pump I added also pumps to return.
I'll run it some more (on oil). I am running it now with bypass closed and so far it seems to be running as it was, knock on wood.
I will have to use what Honeywell calls the "digital input", which will send the valve to 0% (bypass) upon a signal, which will have to be when the oil boiler is off and the heat is coming from the tank. That is, the flow changes direction and the mixing valve has to be open to the tank when extracting heat from it.
If my current no-bypass run looks okay, next time I'll try it with the mixing valve "in the mix". Perhaps the constant seeking previously (before I learned the secret) had something to do with it. Or, it's flow resistance of the valve or something.
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I went through another cycle, this time with the mixing valve operational.
I have to say, it really kept the return temp at 160 setpoint pretty well.
As far as the heat bleed, I previously had to turn down the boiler pump (infinitely variable but not auto ecocirc vario) because of that problem. On this cycle, despite the 160 return, the boiler temp kept climbing, so I bumped the boiler pump speed up a bit from 3.5 to 4.5 (on a scale of 1-7). That brought the boiler temp down and it continued to run until the buffer tank was nicely filled.
It was definitely heating the house though, even with the zone circs turned off. I have temp sensors on the in/out of both zones, and it was doing a differential of maybe 40 (180/140), maybe less ! Without the zone circ! So yes, a couple of zone valves are in my future.
Again, I guess I could replace the flo checks if they weren't needed-not sure if there is room for both (see picture), and access is tight. How about if I put them on the return? Very accessible, and it would stop the loop. I guess there would be some ghost flow, but would that be big?
Can anyone recommend a zone valve?
![[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime](https://www.hearth.com/talk/data/attachments/177/177257-6a4d318a80fd631873c1925063d0fb08.jpg?hash=V06Vk8JxIr "[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime")
I have to say, it really kept the return temp at 160 setpoint pretty well.
As far as the heat bleed, I previously had to turn down the boiler pump (infinitely variable but not auto ecocirc vario) because of that problem. On this cycle, despite the 160 return, the boiler temp kept climbing, so I bumped the boiler pump speed up a bit from 3.5 to 4.5 (on a scale of 1-7). That brought the boiler temp down and it continued to run until the buffer tank was nicely filled.
It was definitely heating the house though, even with the zone circs turned off. I have temp sensors on the in/out of both zones, and it was doing a differential of maybe 40 (180/140), maybe less ! Without the zone circ! So yes, a couple of zone valves are in my future.
Again, I guess I could replace the flo checks if they weren't needed-not sure if there is room for both (see picture), and access is tight. How about if I put them on the return? Very accessible, and it would stop the loop. I guess there would be some ghost flow, but would that be big?
Can anyone recommend a zone valve?
While I'm waiting for two Taco Zone Sentry valves to arrived, I managed to add a couple of relays to sense current in the pellet and oil boilers and close and open the Digital Input terminals of the Honeywell controller. When contacts are closed, Digital Input sets output to 0%, which opens valv e to tank, which allows zones to be heated by the tank. When either boiler is on, contacts open, and the Controller sets the % output according to the setpoint. 100% is all tank bypass, and 0% is no tank bypass.
Here are a couple of pictures of the tank bypass mixing valve and input tee.
![[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime](https://www.hearth.com/talk/data/attachments/177/177412-cfd58fbfdc7846da5e2893d38880e2e2.jpg?hash=NwWhyZqa3j "[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime")
![[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime](https://www.hearth.com/talk/data/attachments/177/177413-effa521f31de49034cf13d1e47894b38.jpg?hash=8eCMLgABqY "[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime")
Here are a couple of pictures of the tank bypass mixing valve and input tee.
I installed the two Taco Sentry zone valves, the check valve and relocated the Spirovent.
Not leaking yet, but haven't heated up yet (tomorrow).
I added another 40va transformer; the valves are efficient on holding, but it supposedly takes 11 watts while charging (about 30 seconds). The capacitor provides the valve closing energy. Anyway, the existing zone valve controller's 30va transformer is powering the mixing valve and its controller. The new transformer powers the zone valves and the thermostats.
The thermostats switch on the zone valves, and end switches on the zone valves switch on their respective pumps via the original pump controller.
Here are a couple pics. Please excuse the mess, crappy looking solder joints, etc.
![[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime](https://www.hearth.com/talk/data/attachments/177/177536-30cb899bc769831eff2a8224426a2ab4.jpg?hash=f6dxhlPmEe "[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime")
![[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime](https://www.hearth.com/talk/data/attachments/177/177537-3a7cc03c699094aa1db40347ad0d933f.jpg?hash=qDZFmmfIO- "[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime")
Not leaking yet, but haven't heated up yet (tomorrow).
I added another 40va transformer; the valves are efficient on holding, but it supposedly takes 11 watts while charging (about 30 seconds). The capacitor provides the valve closing energy. Anyway, the existing zone valve controller's 30va transformer is powering the mixing valve and its controller. The new transformer powers the zone valves and the thermostats.
The thermostats switch on the zone valves, and end switches on the zone valves switch on their respective pumps via the original pump controller.
Here are a couple pics. Please excuse the mess, crappy looking solder joints, etc.
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Looks nice, now your a full fledged member of the point of no return club. This is the type stuff you get done when the wife goes on vacation.
No kidding.
In the "Nothing's Easy" department, there seemed to be pressure creep after I refilled. I set the pressure down on the Watts makeup valve and bought a replacement at the plumbing store. It seems like it might be holding now. I'm not crazy about replacing it: the original plumber seems to have used some kind of hardening plumbers dope on the threads. Thankfully, on the Watts, one end is a union. I just rather not take the chance, so I'll keep looking at the gauge and cross my fingers.
Still haven't heated it up yet.
Heated it up. Still hunting. I'm worried that B. Rohr's post about having too big a Cv for a Mic valve might be a factor. Still messing with I and D.
Beagle Dad
Member
The CV of your valve should be in the range of 0.7 to 1.0 times the maximum expected flow. This will give a 1 to 2 psi pressure drop across the valve at full flow. CV= USGPM/ SQRT(pressure drop across valve at full flow).
The valve is Cv is 29.2. The pipe is 1.25".
Here is my pump curve. I have the setting at 5. I have no idea what my head loss is to find flow. It pumps through a loop with 2 check valves, a thermomix boiler protection valve, a spirovent, the tank, and not that much pipe-maybe 25 feet.
From the curve below, using pump setting 5, the middle of the curve would be 6 gpm.
I guess that would mean the cv would be way high?
I don't think I'll ever replace it, so I guess I'm screwed.
I always thought bigger (cv) was better.
![[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime](https://www.hearth.com/talk/attachments/vario-pump-curve-webp.177565/ "[Hearth.com] Using Mixing Valve on Tank to Maximize Buffer Use and Pellet Boiler Runtime")
Here is my pump curve. I have the setting at 5. I have no idea what my head loss is to find flow. It pumps through a loop with 2 check valves, a thermomix boiler protection valve, a spirovent, the tank, and not that much pipe-maybe 25 feet.
From the curve below, using pump setting 5, the middle of the curve would be 6 gpm.
I guess that would mean the cv would be way high?
I don't think I'll ever replace it, so I guess I'm screwed.
I always thought bigger (cv) was better.
Other than the control issues, which is big. I think I might have done a bad move in relocating the spirovent where I did-now it seems the zones won't clear the air as well as before-plus the tank top will see the same hot water as closer to the boiler, except when recirculating. Perhaps another spirovent? Also thinking of changing swing check to spring.
I'm thinking of not commenting on this thread anymore since it really highlights my dumbassedness.
I'm thinking of not commenting on this thread anymore since it really highlights my dumbassedness.
Is the actuator removable from the valve, if so in the long it might be the least cost fix. Would think a 3/4 valve with a cv between 5 and 8 would do it?
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