Zone Balancing, Boiler Protection, Buffer Piping/Control

SuperJ

I know you're being cautious because this is rework. But I think you're on the verge of overthinking things (probably a good thing), but don't get too worried about some minor variences.

D107

Yeah it's been a long haul; trying to nail this thing down so I can move on and not deal with this so much. Not really worried about nailing down exact flow from each zone etc, but the noise is a deal breaker; if you install circuit setters you don't want to get the roar every time you throttle only to the 1 o'clock position.

gaabbee

I have a concern about the setup but I'm not sure how it's going to effect your system. The 1 inch taco 3 way i series valve mentioned only has a cv of maybe 4.5? Will that limit your gpm too much?

SuperJ

There seems to conflicting information. Looks like you want the Union connection for sure if you go with 1", the 4 way has a higher Cv than the same port size 3way.

the older catalog (I think 2009) has the low Cv


The newer one:



The Caleffi thermomix has a high Cv:

gaabbee

....well that explains why I may be having flow problems on my system wow

D107

Cv terminology is a new world to me. I'm guessing Caleffi's 10cv is considered adequate for my setup since 10gpm is about the highest flow my system will see. Not sure what the pressure drop would be. Is Caleffi's 'thermomix' the same as 'thermoprotec'? They both list as item 280.....
Also was wondering if such valves are isolated with ball valves or flanges like circulators are for quick replacement. Apparently some have unions; and I believe they require a ball valve somewhere in the bypass.

SuperJ

Cv is a coefficient that I this case indicates the GPM at which the pressure drop thru the valve will equal 1 psi.
At first it sounds like higher is always better, but for modulating valves you need a bit of control authority to keep the valve from behaving like a light switch. Generally speaking residentially you typically try and match the Cv to your flow rate. A Cv of 10 would be appropriate but anything from 6-12 would likely work as long as your pump has the capacity. Going a bit higher may save some pump energy over the years. You probably don't necessarily need to be at 10gpm unless you spend a lot time with all your zones calling simultaneously with 58kbtu output. Somewhere between 6 and 10gpm would probably be fine. You can tweak your primary pump speed to find the sweet spot.

hot_rod

> @D107 said:
> Cv terminology is a new world to me. I'm guessing Caleffi's 10cv is considered adequate for my setup since 10gpm is about the highest flow my system will see. Not sure what the pressure drop would be. Is Caleffi's 'thermomix' the same as 'thermoprotec'? They both list as item 280.....
> Also was wondering if such valves are isolated with ball valves or flanges like circulators are for quick replacement. Apparently some have unions; and I believe they require a ball valve somewhere in the bypass.

It is a good idea to have isolation valves around any serviceable component

The 281 assembly includes the circulator and 3 iso valves in the assembly

A properly designed protection mix valve should not require a balance valve in the bypass

Remember the 18 degree differential, a 122 degree element with the 18 differential would have the bypass completely off at 140

https://www.caleffi.com/sites/default/files/styles/product_photo/public/file/281064wyp_0.jpg?itok=A1dDxAY1

D107

@hotrod wow what a cadillac that 281 is! Is the included Wilo circ useful for my setup? Warms the return water faster? Obviously requires power whereas I think 280 does not. How far can either or these be placed from the entry point of return into the boiler?

hot_rod

We build the 281 for solid fueled boilers mainly. The built in pump serves as both the boiler and system pump

Commonly it is pumping directly to a buffer tank so it is plenty of pumping power for the boiler and piping connected

Same with your system it would flow the boiler to the Reverse indirect

A second Circ sized to the distribution

Either you supply the pumps, or buy the block with everything in one box

It’s the same valve mechanism in the 280 and 281. Pumps change from time to time I believe we still have Wilo brand Star series

D107

Ok I edited a Wall diagram for Boiler Protection based on the advice received here and attached @SuperJ 's clearer one. The attached photos supplement this. I believe this avoids a bull-head tee above the Turbomax.
If anyone sees a problem with any of the piping, let me know. I will then move on to the controls aspect.

1. The diagram shows 1” secondary piping to heat load. All near boiler piping is 1.25” but perhaps no problem if it’s 1” from top of turbomax leading up to secondary ∆P VR1816 constant pressure circulator(?) Heating lines are all ¾”.
2. Turbomax already has a hygroscopic air vent; additional can be placed on top of header bushed for a ¾ vent if required. Should it be Hygroscopic or standard auto-vent?
3. Do both headers have to be equal in length? Is 16 inches too long?

SuperJ

I don't disagree with anything in your drawings, but I would do a detailed schematic of all your components. Don't worry about the correct symbols (just label things).

Did you swap your pumps and play with the flow controls? I would do this first to see if the effort to rework the zone flow setters is justified.

You've got a lot of nice pieces in your system. Is that a demineralizing filter on the makeup and mag filter on the boiler inlet?

• The port size on the turbomax is 1.5", that's plenty for a header that will typically flowing at less than 10gpm. I don't think it's worth the cost or effort to upsize to 2".
  
• You shouldn't need a flow control beyond your pump on the primary, but if there is one (looks like you own one already) it should be on a primary only (not in the header section) section of the pipe inside the near boiler piping. Preferably between the discharge of the primary pump, and the tee to bypass to the thermostatic valve.
  
• 16" headers will be fine, in your case the tank will always get the left over primary flow, so it's not a pure header in the sense of multiple pumped zones pulling off a common pipe.
  
• Turbomax aquastat setup as zone 4 with priority enabled on ZVC
  
• I would control the secondary pump off the ZVC, and give a separate heating and DHW calls to the boiler from the ZVC.
  
• That way you can let the boiler run hot on tank recharges, but potentially use the economy settings for heat (with careful experimentation).
  
• Let the boiler hydrostat run the primary pump (on heating or DHW call)
  
• Setup your primary pump speed to give you a 15-20deg delta at steady state fire. You want the lowest pump speed that gives you the delta. If you need to go one notch higher on the pump speed, then you can use a throttled ball valve, or flow control to lower the flow if need be.
  
• I wouldn’t worry about adding additional air vents if the tank has one already and you have the nice Discal.
  
• Your primary pump has to be before the bypass tee going to the thermostatic valve on the return. Looks like you could probably flip the section of pipe with your primary pump and tee around, so the tee is after the pump. (and flip the pump impeller housing).
  

D107

@SuperJ

• Did you swap your pumps and play with the flow controls? I would do this first to see if the effort to rework the zone flow setters is justified.
Not yet--while I know it's not hard to do, I'm a little reluctant to mess with them. Also it seems clear to me that whatever the ∆P circ throttles itself down to, the zones will only be free from noise if no throttling is done whereas we're pretty sure 2 of the 3 zones need to be throttled.

• You've got a lot of nice pieces in your system. Is that a demineralizing filter on the makeup and mag filter on the boiler inlet?
Yes a demineralizing filter and a Magna Clean Professional XP2. I'm happy that the boiler bypass valve will apparently have to be placed before that mag filter on the return so all supply water would have to pass through the filter.


•The port size on the turbomax is 1.5", that's plenty for a header that will typically flowing at less than 10gpm. I don't think it's worth the cost or effort to upsize to 2".
The port size is actually 1.25" for boiler water and 1.5 for DHW ports. So if we have to raise to 1.5, seems like we might as well go to 2" to make sure the de-coupling works unless you think that's a waste. Also, can the first portion of the takeoff to the secondary circuit be 1" even if it soon transitions to 1.25" at the circ?

•You shouldn't need a flow control beyond your pump on the primary, but if there is one (looks like you own one already) it should be on a primary only (not in the header section) section of the pipe inside the near boiler piping. Preferably between the discharge of the primary pump, and the tee to bypass to the thermostatic valve.
Yes I think one our flow controls --currently in the lower header section--would be removed and the other we'd hoped to put in the vertical pipe near the end of the secondary return before it tees into lower header. Originally both of these had to be put in to stop migration between DHW and heating zones. Placing it where you suggest it would seem to have a different function whatever that would be. Your basic point seems to be that with hydraulic separation, no need for flow control (check) valves; separation should stop migration.

• 16" headers will be fine, in your case the tank will always get the left over primary flow, so it's not a pure header in the sense of multiple pumped zones pulling off a common pipe.
• Turbomax aquastat setup as zone 4 with priority enabled on ZVC
Gaabbee said: I1 and I2 wires can either be from the turbomax aquastat to the hyrdrostat OR turbomax aquastat directly to the ZVC. I1 and I2 are the turbomax aquastat wires. The hydro stat has the ability to run this with priority but after talking to both companies I felt that routing it directly to the taco was the better choice. The Zvc doesn't have to worry much about the voltage drops and to me is easier to work on.

• I would control the secondary pump off the ZVC, and give a separate heating and DHW calls to the boiler from the ZVC.
That means primary circ will run on all calls whether DHW or secondary, but only primary will run for DHW?

• That way you can let the boiler run hot on tank recharges, but potentially use the economy settings for heat (with careful experimentation).
• Let the boiler hydrostat run the primary pump (on heating or DHW call)
• Setup your primary pump speed to give you a 15-20deg delta at steady state fire. You want the lowest pump speed that gives you the delta. If you need to go one notch higher on the pump speed, then you can use a throttled ball valve, or flow control to lower the flow if need be.
I'll have to try using the ball valve for throttling--should ideally be Globe valves for that right--and see if we get the noise problem. Maybe if the ball valves throttle without noise we can keep circuit setters fully open and use them just to read gpm. Perhaps when I insulate all the pipes with 1" fiberglass noise/vibration will be reduced but I can't count on that.

• I wouldn't worry about adding additional air vents if the tank has one already and you have the nice Discal.
Yeah, though the top header may be higher than the Discal but maybe not an issue.

• Your primary pump has to be before the bypass tee going to the thermostatic valve on the return. Looks like you could probably flip the section of pipe with your primary pump and tee around, so the tee is after the pump. (and flip the pump impeller housing).
that seems doable but not sure why impeller housing has to be flipped if circ orientation will be same. but that location will be good for the 1" bypass pipe down into boiler return.

SuperJ

With a delta p pump and circuit setters I don’t think need or want an additional flow control on the zone return. The delta p pump will work better if most of the pressure drop is in the zone (not the common heating piping). A flow control on the heating return will add a pressure drop and change the curve, which will make it harder to get consistent flow in each respective zone with various combinations of zones calling simultaneously.

In the primary loop you really only need a flow control if your are getting too much flow at the lowest constant speed setting in the primary pump. This flow control (if you out one in) needs to be on the boiler side of the tees to heating Or if the pump settings are in too big of increments and you need to fine tune. You could use a ball valve to do this, no need for a globe. you’ll probably have valves around you thermostatic return protection valve anyways. Remember the flow will be close based on the pump setting and valve is just to fine tune. A globe valve would only be necessary if you were way over pumping your primary loop.

I guess I’m trying to say don’t go and buy anymore flow controls.

There are a couple different ways you could wire the ZVC to the hydrostat. For maximum flexibility it makes sense to wire the heating call separately from the DHW heating call. That way you can play with the economy settings that might help utilize your buffer. It just means using a 4 conductor wire between the ZVC and hydrostat instead of 2. So no real cost or effort difference.

The ZVC has a set of dry contacts for heating and a set for DHW. (Top left). These can be connected to the boiler’s hydrostat heating and DHW terminals.

The primary pump could run off either the hydrostat or the ZVC pump contacts. The secondary pump would run of the ZVC pump contacts in series with the zone 4 NC contacts. This will stop the secondary pump when zone 4 calls.

When looking at the Taco wiring diagrams, remember you have a primary system pump and secondary pump, but no dedicated DHW pump or valve.

D107

Currently schooling myself on the hydrostat and ZVC 404 and direction of control actions. I'm slowly starting to understand it. Thanks for underlining the options.

Note that I experimented with throttling two of our zones with a combination of the circuit setters and ball valves and I think doing both may allow me to throttle enough without noise. With just the ball valve alone I had to turn it halfway down to see a movement in the gpm reading. Generally at most I’ll probably need to throttle no more than .5 to 1gpm per zone to give the third one what it needs. So as long as the ball valve is built for this kind of half-way or quarter-way operation, no problem.

I also noticed that with VT2218 Fixed speed 3, we’re probably a little underpumped. Meaning that when the two largest zones call for heat at the same time the respective gpm are 2 and 2.5gpm, the smaller zone doesn’t get as hot as it would if it were called alone—the last radiator suffers a bit more (that’s where the thermostat is) and the zone will call again within a half an hour to finish the job. (Note rads are piped in series.) Hard for me to understand why, if the thermostat was satisfied enough to end the call for heat, why it would call again so soon. (The t-stat always keeps the room at the set temperature.)

hot_rod

Really a ball valve is not an ideal throttling valve. Very little change until you squeeze them way down, then the resolution becomes crappy. A tiny movement can make a big flow change,

I suggest balancing with a ball valve in its mid range, choking down too much makes it hard to get small, accurate balance.

Also too much throttling on a ball valve can cause velocity noise across that sharp edge in the ball. Delta P circulators help with zoned balanced systems as they will modulate to prevent over-pumping.

That being said perhaps the most common balance valve out there is the B&G Circuit Setter, a ball valve. A precision ball

D107

@hot_rod Thanks, I haven't gone much beyond a mid-range throttle on the ball valves--not shown in photos below–– beyond which I start to hear the noise. I also put a little throttle into the Caleffi Circuit Setters.
As you can see from the photos, the setters do not have the 4-5" of straight run before them so i think that's why the noise is there. Which means I may not have the ability to fully use the circuit setter throttling unless I move them somehow. However, SuperJ has suggested switching the circs first and seeing if the ∆P circ quiets things up. I would need a bit more courage than I presently have to start messing with those. As it is now, I got it pretty quiet using both circ setters and ball valve.