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Converting my zone valve arrangement to a hybrid of zone pumps and valves

I recently moved, and the expansion of baseboard heating pipes won't let me sleep. I've addressed the issues where I can, but the origins of most noises are inaccessible.
The boiler is non-condensing--a Crown boiler of model BWF162EN. The circulator pump is a Taco model 007-F5. It has six heating zones plus an indirect water heater. The configuration is as shown: https://www.dropbox.com/s/sc9zjbphkqygvag/Current Configuration.jpg?dl=0
As a side note, I replaced a powerhead on a valve that had been left stuck open by the previous owners, which serves a garage unit heater. Now that the valve is closed, the circulator rattles when a zone calls it to run. I think cavitation. The noise stops if I force open the unit heater zone valve to open a second loop. Placement of the expansion tank (downstream of the circulator) is actually an approved location per the boiler literature, even if the indirect doesn't have its own pump as per (piped as Fig 27 rather than Fig 28): https://www.dropbox.com/s/zi7xzmc58ttyn0c/Boiler Mfr layout details.pdf?dl=0

I've been thinking of ways to reduce the expansion noise, listed here in descending order of preference. I'd like to get your thoughts on the feasibility of Option 1 (and if it won't work, then Option 2, etc). I've used Powerpoint to draw schematics of Options 1 and 2.

1. https://www.dropbox.com/s/7waibkbe07mubjr/Option 1.jpg?dl=0 Convert the problem zones (B and C as pictured) to have their own circulators and low-temp loop (I'm thinking how a low-temp radiant floor loop might be added to someone's house).
1a. Option 1 with a buffer tank. https://www.dropbox.com/s/q6czoksh80lhvpr/Option 1A.jpg?dl=0
2. https://www.dropbox.com/s/odgj7xc9vzvum5u/Option 2.jpg?dl=0 Convert the whole house to primary/secondary to control for a low temp.
2a. https://www.dropbox.com/s/0gomnzxsy8gpooy/Option 2A.jpg?dl=0 A variation of Option 2 with less precise low-temp control but greater temp capabilities elsewhere.
3. Install a buffer tank, with a coil connected to the boiler loop, to store water around 120 F (reset if needed on outside air temp). A secondary circulator would distribute water at the lower temp. I don't have room for this without some difficulty.
4. Install a condensing boiler. Not sure how low their temps can go, but I imagine I'll run into problems with the indirect water heater, turndown ratio and/or design day temperature requirements of other zones. Also expensive.

Wrt Option 1, the areas where I could really use input are:
1. Assuming I can keep the spaces comfortable with water around 110-120 F, would it likely eliminate the noise? Ie is this exercise even worthwhile?
2. Is there an "out of the box" ready controller that is smart enough to manage the zone pumps, boiler enabling and three-way valve temperature control? Maybe include a hot water reset for the valves? I assume best approach would be to have the zone pumps run continuously and have the boiler and it's pump cycle on based on a call from any of the zone valves or three-way valves. Currently I have a Taco ZVC404. The Zurn Application guide shows a similar setup but doesn't mention the valve control method... https://www.dropbox.com/s/38pq73c7ddnaxda/Zurn Controls.pdf?dl=0
3. I'm concerned that if only zone B or C is operating (which will often be the case if they are using 110 F water), then the boiler may cycle frequently because it will be circulating most of its 180 F water back to the inlet (the water temp is not adjustable at this boiler, i assume it's around 170 or 180 F).
4. I assume I'd have to balance the bypass line to maintain a 150 F boiler inlet while zone B or C is in operation with a return temp of around 100 F. This means a lot of bypass. Will other zones be starved when their valves open? I was thinking a pressure-based ECM pump like the Taco VR1816 could let me minimize bypass flow during these conditions, and then the pump would speed up if a high-temp zone valve opens. Still, I'm not sure if the boiler would have a minimum flow rate requirement. I've found nothing for this in the boiler literature.
5. Given the current pump may already be cavitating, will this bypass scenario just make matters worse? Maybe the variable-speed pump of question 4 will help with this...

For Option 2A, I might ultimately include valving by zone to allow each to be selectable between the primary or secondary circulator.

Any other options come to mind?

This is the room: https://www.dropbox.com/s/r1l0ejtdbnc7fkp/20201117_212347.jpg?dl=0


  • hot_rod
    hot_rod Member Posts: 22,251
    The best option it to limit the temperature swings. An outdoor reset control might help, get you close to constant circulation.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • TheHeat
    TheHeat Member Posts: 7
    hot_rod said:

    The best option it to limit the temperature swings. An outdoor reset control might help, get you close to constant circulation.

    Thanks hot_rod for the tip. I agree. My intuition is that I would have the two zone pumps run continuously (if I could get the controls right--I may need to ask in the controls section) with the boiler pump operating as needed by any of the zone valves or three-way valves.
  • hot_rod
    hot_rod Member Posts: 22,251
    The goal is to minimize the temperature swings, try to get constant circulation. Outdoor reset controls, if you spend the time to dial them in can get you close to constant circulation. i don't think piping changes will help quiet pipes that are noisy from expansion/ contraction.

    Run the lowest possible temperature to get the job done. Either trial and error, or do a load calc, design, and heat emitter match up.

    Buffer tanks are mainly used to lessen short cycling when you have a "fixed speed" boiler and a lot of zones or some micro zones. On a design day does the boiler cycle on and off a lot? If so a buffer could help minimize on/ off cycles caused by an over sized boiler.

    As for adding a radiant loop, if it is below a subfloor, consider the UltraFin product, it could run the same temperature as the other emitters and eliminate adding a mixed down zone. Or pipe in a 3 way mixing valve.
    You may still have cycling issues as you add more, small zones, regardless if they are low or high temperature.

    Turning off the garage unit heater should not cause the 007 to be noisy, as long as some zone is open it should be fine, and quiet.

    What are the gpm requirements of the zones? I prefer zone valves if they are 1- 1.5 gpm requirements.seems overkill to have 6 circs moving only a gpm or so each? A single delta P circ and valves is very common nowadays.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,322
    This was a double post, so I've merged it into one post here. Thanks.