Lochinvar Knight - single pump, 3 zone system

djohn

As the other thread completely evolved from what I originally planned - thanks to SWEI - I now consider a single pump system (no P/S piping) that would run on Alpha pump and 3 zone valves.



Since all I built so far were NTI boiler systems with zone pumps, I really need an advice on how to piece it together. It will run off WHN110, with 1" piping. 1st zone is slab, 6x 300' loops. 2nd and 3rd zone will be joist trak, 8-9 loops.



1. No low loss header or hydraulic separator needed?



2. Is differential pressure bypass valve required?



3. Y strainer? (never used it with NTI either)



4. How much of temp difference can zone valves handle? (R-10'd slab vs R-19'd joist trak) - so I can avoid a mixing valve.

5. What model of zone valves, normally open or closed?

6. Without closely spaced T's, do I need additional check valves?

7. Anyone uses RHT manifolds? Last time I did was 5 years ago. They come with temp gauges, air vents, can be ordered with flow gauges. SS vs bronze?

8. Anything else I should look at with valve zoned system?



So far my shopping list includes the boiler, Alpha pump, RX-30 tank, vortech air separator, combo fill/check valve.



Attached is Lochinvar's manual page that I am using to design my system (no DHW though)

Ironman

Multi Temp

That's for a single temp, multi zone setup. You'll need to design for a multi temp, multi zone.



The WHN can handle 3 temperature zones, but will always give priority to the highest temp. Lochinvar has a multi temp control that can be added to control 3 mixing valves, but the cost of the control plus 3 motorized mixing valve ain't cheap.



Your slab needs to be controlled based upon outdoor reset to prevent overheating due to the flywheel effect. You can use Lochinvar's setup or you can use variable speed injection mixing such as with a Tekmar 356 and let a thermostatic mixing valve control the max temp to the staple up. But your staple up and the slab have different requirements and need separate reset curves.



Lochinvar's multi temp control is shown in the same area of the manual from where you got your drawing.

djohn

temps

I have used I-series mixing valves before. Would that be a good idea here?



Ex. I had NTI running at 140F supply and slab zone was mixed down to 120F.



Or are we talking about whole another setup here and additional pump is needed? Don't want to burst my single pump bubble



Edit:

Multiple temp diagram is there only with P/S piping. Trying to avoid that, if possible.



Edit2:

Looking at Joist Trak data and based on 20BTU/sqf, and R-1.5 of my floor assembly, which is 3/4" OSB, 1/2" durock and 1/2" stone tile.  - I could run 125F supply, which is awfully close to what my slab would require. So single temp after all?

SWEI

Multi-temp

Is it just two temps?  If so, I'd probably suggest a Viessmann 200W B2HA.  Its onboard controls will handle the external mixing valve (and it has even better turndown than the Lochinvar.)  It will require primary/secondary piping in the size you are looking at, but the savings on external gadgets can be significant.

djohn

temps

It's probably not even 2 temps, as I mentioned in previous post.



If 2 zones with joist trak can run at 125F, I don't see why slab couldn't. I know it could be tweaked down to maybe 110-115F, but being so close to 2nd and 3rd zones, what's the point?

djohn

trying to answer

Just trying to think through some of my questions:



1. No to low loss header required since there is no P/S piping



2. No diff pressure bypass valve because of variable speed pump

3. Yes on Y strainer, per manufacturer guidelines



4. No mixing valve, since design temps on joist trak and slab are pretty much the same - so it effectively is a single temp system



5. Thinking normally open mixing valves, so I get heat when they fail. Makes sense?



6. Yes on check valves because of normally open zone valves (not sure here 100%)



7. Still looking at manifold info. SS vs brass. What about brands like Rifeng or RHT? I like to have temp and flow gauges on manifold and used RHT before.



8. Also, do I need ZVC if I get Sentry valves? Keep in mind it has to be all wired to Ecobee thermostats after said and done.



Please correct me and add any advice you find important in this project.



Edit: 8th question.

SWEI

Run the numbers

I've seen houses like that running design temps of 120ºF through plates and 90ºF for a slab (plus or minus five on all.)  With proper emitter design you could actually series pipe the floors.

djohn

diverting sentry

Would a 3 way diverting sentry valve solve the need for yet lower temp in slab zone?



Also, do I need a ZVC with sentry valves?

Ironman

Circ's

I doubt if you're gonna get by with one circ. Depending on the flow requirements for the floors, they may each need their own circ's. We'd need to know the btu requirements, pipe lengths, number of loops, etc to determine the circ(s).



I think you're gonna find that the slab needs cooler water temps and a different reset curve than the staple up. Again, keep in mind that the slab is high mass and the wood floor is low mass. High mass requires much tighter control as the slab can continue to give off heat for hours after the thermostat is satisfied. If the water temp is controlled properly by outdoor reset, it won't over heat. In fact, when properly set, the outdoor reset can regulate the slab temp to where the thermostat becomes unnecessary. It will act more like a high limit. I've got one right next door that's been running without the stat for three months and it keeps the bldg. heat just right all the time.



I see three options on setting up multi temp zones with the WHN:

1. Use the Lochinvar multi temp control and motorized mixing valves for each temp.

2. Use smart valves for each temp. Or, one smart valve on the slab plus a thermostatic valve on the staple up.

3. Use injection mixing on the slab, plus a thermostatic mixing valve on the staple up. Injection mixing will definitely require more than one circ. Go Tekmar's site and look up their "essay" on it.



It may be possible if your water temp requirement for the staple up is NOT too high above the slab, that you can let the boilers control handle both zones alone, but remember, it's gonna give priority to the higher temp zone. That means when both zones call, it's gonna choose the temp requirement for the hotter zone and both zones will get that temp until the higher one is satisfied. This could cause the slab to over heat. You really need an accurate load calc and design to see if this last and simplest method is viable.

djohn

more details

I have 6 loops in the slab and now figuring 7 and 8 in 2 remaining zones (same area, just longer runs to the heated area) All 300ft 1/2" pex loops.



Using Uponor's table and 10GPM total numbers, I am coming with:



- 3.4ft of head in zone 1 (slab, 6 loops)

- 2.3ft of head in zone 2 (joist trak, 7 loops)

- 2ft of head in zone 3 (joist trak, 8 loops)



If that is correct, then 3.4ft of distribution head plus 1.5ft of boiler head = ~5ft of head for entire system, at 10GPM



Total heat loss is 66kBTU (again it excludes use of the drive under garage) and spreads like this:

- 31kBTU for the basement - ~20BTU/sqf loss

- 19kBTU for the 1st floor - ~13BTU/sqf loss

- 16kBTU for the 2nd floor - ~11BTU/sqf loss



WHN110 and 4,500sqf total floor area average out to about 20BTU/sqf input. Looks perfect to me.



I am fairly convinced that singe temp system will work, although I see potential fuel savings in running the slab at lower temp.



On your points:

1. I have to read on how WHN110 controls temps.

2. What smart valves are you referring to? Sentrys?

3. That scenario erases the single pump idea so lets discuss it if everything else fails



Edit:

Looks like I-series mixing valves require P/S piping and use of 2 pumps.

Any other ideas to achieve lower temp in one of the zones?

Ironman

Your Numbers...

Are not correct because you're using a 20* delta T. You need to be using a10* delta T, 12* max for radiant floors. That's gonna change your gpm and head requirements drastically. You also need to calculate you head losses the zone valves, actuators, manifolds or any thing else in the circuit. Again, I seriously doubt that a single Alpha pump will handle all that.

Why are you so stuck on sacrificing performance and system efficiency for the sake of using only one circ. I can understand wanting to save electricity, but not at the cost of performance. You're probably looking at less than $25 per year to run a 15-58 circ.

djohn

delta T

Hmm... how could I miss that!



Even if numbers are changed, there is still just one Alpha model that can handle it.



Can you elaborate how it's going to hurt this design?

Ironman

Insufficient GPM...

Will lower your btu output and cause striping. Part of the floor will feel warm and part cold.



Why go to the trouble and expense of radiant only to cut corners on circ's and then have a system that doesn't perform as it should?



Don't strain at a gnat and swallow a camel.

djohn

GPMs

I definitely need a good, efficient and long lasting system. Don't want to cut the corners but make it work.



So assuming the slab will require double the original GPM, wouldn't it be enough to just throttle down remaining 2 zones (at the manifold) to achieve higher flow at the slab? Boiler and pump would still maintain the same total GPM and BTU.



If that's out of question, am I coming back to 4 pump design and P/S piping?



P/S with boiler and system pumps doesn't do much on 2 temps, unless I involve I-series mixer, which is even more $$.

Zman

The Wheel...

I believe you can do all this as a single temp system.

Why are you so reluctant to use an alpha(or similar delta p circ) with zone valves for the system side and the 15-58 for the boiler side?

Why do you keep going back to 4 pumps or one pump?

The answer is 2 pumps, primary/secondary.

I would be very reluctant to do a non primary/secondary with 300 foot pex loops.

I don't see the need for a strainer on a new pex system. What are you straining?

This is the most common setup for a reason. It is simple and it works. Don't reinvent it.

Carl

djohn

SWEI

It's all SWEI's fault - believe me



I was set on pump zoning as I stated in the other topic. Then the whole thing evolved to maximum simplicity and he threw and idea of using just one pump. 4 pumps is still my fallback option, as I am struggling to fully believe in single pump system. I do understand pump zoning. Still learning on valve zoning.



And I have to admit - I like the idea of single pump system. And I know that pump manufacturers would hate me because of that. They want me use my old 4 pump plan



For one, head loss is so miniscule - 1.5ft on boiler and 3.5ft on system, then you almost need them combined to take an advantage of alpha's autoadapt.



But then I will be likely losing some efficiency because of same temp in joist trak and slab zones. I am not crying over that or the fact that the whole thing evolved around 20F delta-t, not 10F. I want to see it to believe it.



I am still hoping it's doable with single pump. I understand the concerns because of lack of P/S piping, but even Lochinvar mentions direct pumping in their literature.



Right now I only have slab piping in place, and 2nd and 3rd floor won't be hooked up for a while. So I will likely put it together without zone valve and pipe it directly to the boiler, thermostat to the boiler.



BTW - strainer is mentioned in Lochinvar literature. I run my water through whole house filter and water softener, but I am on the private well. Does strainer hurt anything other than my wallet?

Zman

Single Pump

Notice that lochinvar shows a diff bipass in the drawing. This assures the minimurm flow through the boiler.

If you did an accurate head loss and could assure the flow,one pump could work. With 300 foot loops, I have concerns.

I don't use auto adapt with the grundfos alpha. It is really designed for systems that are always pumping. It will not work at all in on/off applications.I know people who leave it on with closed zone valves, I don't know why.

For 300 foot loops constant pressure 3 would be a starting point.

The strainer won't hurt.

Carl

djohn

DBPV

Isn't differential pressure bypass valve obsoleted by use of variable speed pump?

There should be no additional pressure or flow present between 1-2-3 zones calling for heat at the same time.

SWEI

I'll take my share of the blame

but I overlooked the fact that you had two different types of emitters.  Run the numbers and make sure they can peacefully coexist.

hot_rod

DBPV is obsoleted by

delta P circs, not variable speed circs, per say. The D and the P are the key.



And I agree with the other posters you need to study the operation methods to determine which setting matches you system design.



I use the AutoAdapt on one of my systems that has TRVs, fixed speed on another.



Maybe checkout the webinar Siggy did for PM mag on delta circs, or some of generic articles on the products.



There is a bit of learning required before you purchase and install these newfangled pumps.



Don't just install them because a glossy ad in a magazine told you they are better for your system



And at the end of the day, or these long threads, only YOU can decide which technology will work best for YOUR design.



We are still aiming at a moving target with you system design, component selection, and questions.

Zman

Bipass

Traditionally we use bipass valves to prevent deadheading circs and to keep the system at a constant pressure. This use has been replaced with delta p circs.

The lochinvar drawing for a single pump system is using it to maintain minimum flows through the boiler as well.

Carl

djohn

adventure

I totally understand and agree. It's quite an adventure to me.



Grundfos is a whole new thing to me. Always used Taco.

Zone valved system is a whole new thing to me. Always used zone pumps.

Single pump system idea just blew my mind.



Question on slab vs joist trak and possibility of need of bigger temp difference (joist trak looks like 125F supply for my system).

How one would achieve a lower temp in one of the zones in single pump system?

- is I-series mixing is out of question because it needs a P/S piping?

- would simply reducing the flow through slab zone manifold do it? (manually tweaking the manifold valve or loop valves)

Weezbo

ok just to throw a monkey wrench in the mix,

Variable speed variable voltage with an individual reset curve zone valve ,...

i would think being very similar then either a variable temp or set point temp would aid in the bounce or speed bump .

the only minor technicality goes back to differential pressure ,

he he and finding differential set point control valves small enough for a capable match.

i tend to think you will always see the pressure differential being the key minor technicality in very large systems that can be game busters on ever getting or keeping everything perfect .

smaller systems , i think the complexity might not be as drastic of a game changer however , no matter what , you have to find what you can "Live with"

*~//: )

because Perfection , ...is forever receding.

or as the Great Tagathata once said ,



"The nature of all component things , is decay."





Weezbo.

djohn

Boiler

It looks like the major missing piece of the puzzle, boiler, will be arriving here next week so I will keep you guys posted on the install.



Thanks for all help and suggestions.

I am still researching manifolds, which I think is worth it's own thread.

Ironman

Manifolds

Rehau or Caleffi. You'll have no regrets. Stay away from the Chinese ones, they're junk.

djohn

chinese

Bob is doing pretty good at selling Caleffi and I might bite.



And yeah, I have heard that before. So RHT is chinese? I have seen indonesian and chinese sites of Rifeng, but wouldn't think they are chinese either



BTW, as we speak, one of the RHT's I have installed (2006 I think) just started slowly leaking through the flow meter. Really acidic water though.