Maintaining minimum flow w/o P/S -differential bypass? bypass zone? flow switches? ideas?

keyote

Hat yes I think youre right theres great tech with pumps and modcons with controls and new configurations but grafting them on to old systems and old building envelopes doesnt deliver the promise you have to be all in.you start with the building envelope, fenestration etc and build from there now you can use low temp emitters and mod cons and can start to play with solar and ecms and fancy controls and configurations;- you know stuff you engineers love because the math is important at that grain, and rule of thumb disasterous

Gordy

keyote said:

Gordy
"Now apply this to a direct pumped boiler that is NOT forced to maintain a delta. As the boiler fires on a call from cold start the initial efficiency will be higher because the rwt will initially be lower. ".....
Im trying to understand this, Its important to me because im leaning to this VT2218 DT pump partly because its an ecm whose is curve is wide enough for me on the low and high sides, admittedly it also appeals seems because it helps my amatuer mind with thinking about control because it partitions aspects that otherwise interact and get my head spinning-Or so I think
.
Considering your comment is hard because I dont have experience thinking about the time scale for various systems which i think is the crux, but I may be clueless, Im imagining some huge old atmospheric systems pumping large amounts of water needing to be heated much hotter and this all takes some time to ramp up but the ramp up does a fair amount of partial load meeting, and in this system if it were on a modcom which i dont think it would ideally be then a significant portion of fire time would be essentially warm up.
But [and i could be wrong] in a system like radiant or a small baseboard the water can make a full circuit in seconds and would be better off being at the right temp asap, its warm up is too low temp, and happens to quick to make any meaningful contribution to load.This worry about high limiting on start up I have and Hat experienced is possibly helped by micro version of this but i think thats more a matter of syncing than efficiency, But i may be not getting your point.

My point is how mass, and btu transfer effect the systems performance, and operation,which is indicative to radiant systems. You have effectively not much trying to suck the btus out of the tubing on the emitter end in your radiant detail.

keyote

Brewbeer yes you are correct that mixing will mess with RWT on condensing efficiency, while you were typing i was reading the charts gordy posted and while i admit it probably wouldnt work because of that im curious. if im doing 140 dhw usually and 100 SWT radiant that day im taking 20% of the hot and returning 20% at 85-90 but i dont know what my delta t is on the indirect and to really study this you would want a simulator maybe siggys software would give a rough idea. This is because while you might smash the idea in one scenario it might be that changing indirect size and indirect delta t or storage temp could make it work. It might be that it works great on only certain types and size systems but not others. for instance on emitters that wouldn't need mixing, RWT becomes a non issue, and the indirect could be sized to almost always have the ch water go through it first.
Before you get too involved realize this is all half in jest i wouldnt dream of doing this if i wasnt sure it would do better and i dont think its possible to know that without some robust modeling software and my gut agrees with you with radiants inherently low water temp its a long shot that my system is an ideal candidate for this configuration.

hot_rod

Hatterasguy said:

hot rod said:

I thought this 15-42 VS pump was no longer available, but I see Supplyhouse.com still offers it. It should communicate with the Lochinvar 0-10VDS signal, and I think the curves work out, although not sure what you have decided on the required flows?

Having the circ take orders from the boiler control makes most sense, I think.




SH.com does have all the manuals for it on the page.

It's not for the cheap of pocketbook shopper.

That is a fine pump and would do a fantastic job with the KHN. But, as you noted, it's pricey.

Why not use the Nimbus controller with a conventional PSC circulator to achieve close to the same results at 1/3 the cost?

http://controlresources.com/pdf/Nimbus.pdf

It is understood that circulator would need to be selected carefully and not be too large as it cannot get down below 35% or so. The boiler will likely be overpumped slightly at very low modulation levels.

Balancing the system by limiting flow to only the amount needed at design will assist with the low end.

As an example, if the system was balanced so the maximum flow at design was 5 GPM (for 50K load), the circulator could get down to 1.75 GPM at minimum modulation. A bit overpumped for 8K but not catastrophic.

It would make a fine boiler pump setup.

Sure, that is another option with the Nimbus.

Ideally the perfection its here would like an ECM solution. Personally I would prefer a small 120V ECM solution that just needed a pair of control wires to the board. The control logic is already onboard the KHN, I'd rather not bring another component into the mix, someday it will need service or replacing, will it be available in 10 years?

The circ we all want is already out there in a few brands and a good selection of sizes, we just live in the wrong country to have easy access to it.

The next question is cost. What is a contractor willing to spend for a small 0-10 ECM circ? It seems that 400 plus range (online) of the current PSC, 0-10 Grundfos 15-42FVS may be a deal breaker. I doubt an ECM version of it would be cheaper.

That being said, since all of Europe requires only ECM, maybe prices will drop and go below PCS, since there are fewer and fewer markets for PSC circulators? We have already seen how production numbers have dropped the price of the Alpha since it came over here.

I don't remember that Viessmann circ 15-62, I think, being an ECM. Or if it was a 0-10 or PWM pump.

keyote

Gordy

Im going to reread the lochinvar manual again, and go back into training videos its a lot to absorb. The ecm guys all say 50% savings out of the box I built a hydro electric system oin my Idaho homestead, and when i changed to a permanent magnet generator that was true.
Also remember using the boiler to control pump they want P/S so its two pumps.
That said there are at least two open questions about the 2218, one is your comment about not wanting to hit DT too fast an my wondering if you felt that way about radiant specifically or more with larger slower hotter systems. From other comments i get the impression you dont like DT pumping but im not clear on why except the above.
The other question is is how we got started on all this which is basically what is causing Hats problem and how can i avoid it.

This may be tied to low flow but hat says its impossible for the pump to pump less than the minimum flow at the low heads the smallest calls will have. But i have no idea what happens to those extra gpm is a bypass loop going to shunt them back through boiler? Now that might be a kind of faux primary loop but can the burner hold steady with a lot of water coming back almost same temp? I could zone two floors to avoid a call on a 65 degree day for less heat than the 8500 lowest, modulation, but even then while the required flow would be more than 1 gpm it would be less than what hat says the pumps minimum is so again where the extra flow go? But this pump has the lowest curve thats also high enough. still I think ganging floors is more efficient than a buffer.
But i think you mentioned and the manual talks about a way to do something like that on a case by case basis i guess it holds calls sometime until another comes in and or adds a call it thinks is close to need a bit sooner, so i dont think the modulation is an issue if hat is correct about the flow and someone can expplain where extra flow goes. My drawing was an attempt to add mass on low load calls and soak up flow but iys going to mess up condensing.
The other possible cause of Hats issue was two controls always mis-anticipating each other, and I am thinking can be solved by ramp control or other method if we are not asking the boiler to manage both. I thought the problem with that was the ecm had smart software the boiler couldn't override but since Loch doesnt even want dumb VS boiler controlled without P/S i think its more involved but i talked again with them yesterday and they cant explain other than "algorithm"


This VT2218 is the only ECM pump whose curve is really good.But again I think theres something about how Im thinking about pump controlling DT and boiler controlling water temp youre not likeing but im not clear what.

Gordy

hot rod said:

Hatterasguy said:

hot rod said:

I thought this 15-42 VS pump was no longer available, but I see Supplyhouse.com still offers it. It should communicate with the Lochinvar 0-10VDS signal, and I think the curves work out, although not sure what you have decided on the required flows?

Having the circ take orders from the boiler control makes most sense, I think.




SH.com does have all the manuals for it on the page.

It's not for the cheap of pocketbook shopper.

That is a fine pump and would do a fantastic job with the KHN. But, as you noted, it's pricey.

Why not use the Nimbus controller with a conventional PSC circulator to achieve close to the same results at 1/3 the cost?

http://controlresources.com/pdf/Nimbus.pdf

It is understood that circulator would need to be selected carefully and not be too large as it cannot get down below 35% or so. The boiler will likely be overpumped slightly at very low modulation levels.

Balancing the system by limiting flow to only the amount needed at design will assist with the low end.

As an example, if the system was balanced so the maximum flow at design was 5 GPM (for 50K load), the circulator could get down to 1.75 GPM at minimum modulation. A bit overpumped for 8K but not catastrophic.

It would make a fine boiler pump setup.

Sure, that is another option with the Nimbus.

Ideally the perfection its here would like an ECM solution. Personally I would prefer a small 120V ECM solution that just needed a pair of control wires to the board. The control logic is already onboard the KHN, I'd rather not bring another component into the mix, someday it will need service or replacing, will it be available in 10 years?

The circ we all want is already out there in a few brands and a good selection of sizes, we just live in the wrong country to have easy access to it.

The next question is cost. What is a contractor willing to spend for a small 0-10 ECM circ? It seems that 400 plus range (online) of the current PSC, 0-10 Grundfos 15-42FVS may be a deal breaker. I doubt an ECM version of it would be cheaper.

That being said, since all of Europe requires only ECM, maybe prices will drop and go below PCS, since there are fewer and fewer markets for PSC circulators? We have already seen how production numbers have dropped the price of the Alpha since it came over here.

I don't remember that Viessmann circ 15-62, I think, being an ECM. Or if it was a 0-10 or PWM pump.

I agree with hot rod. I would rather spend the extra dollars on a vs circ that loch recommends already, and eliminate a third party control. For the reasons stated.
Effectively your paying for the smart system on the boiler to have the option to utilize the right circ. The curve of the three vs circs grundfos offers can get down to 1 gpm with less than 2' of head. More so the 15-42.

keyote

Hot rod there are tons of 0-10volt input PWM output to interface american HVAC equip controls with ecms anything from a $50 circuit board to wilos two pump interface at supply house for $175 its done all the time commercially but at the VT -VS- Alpha- bumblebee level its a bit expensive compared to pump. Still its not really the problem I would do it in a minute except lochinvar doesn't even care about the ecm issue
[in fact they didnt even know what an ecm pump was after three techs and two marketing guys they only vaguely seemed aware there was something odd about the bumblebees and recalled someone once asking about an eco something]
- they dont want any type VS pump boiler controlled without P/S, and they cant explain why except "The engineers said something about algorithm", so if you are controlling your pump ecm externally you don't really need to worry about PWM because its onboard. BTW you could make your own Aurdino interface in an hour,im sure theres all sorts of plans to download.

keyote

Hat why would you prefer a VS over a ecm if you could get it in a size you liked. ecm is half the energy even without the smart software, now while the smart software is nice in situations with dumb boilers i would like a ecm that starts at 0/0 and climbs to various high curves but without smarts so the boiler could completely command it. either the boilers could put a PWM circuit in or the pumps could have a 10-0v input doesnt matter thats easy, what seems to be the problem no one can explain is why the boiler cant control even a dumb VS without P/S

Gordy

READ THE MANUAL PG. 39, and 56 you have 4 options.

You have three grundfoss vs choices that will plug, and play nice.

No they are not ecm, but we are not talking hundreds, or thousands of watts either.

Lochinvar wrote it.

Gordy

To make things play well together the boiler controls need to control the circ. It decides hey I'm climbing to fast speed up the pump speed, or hey I'm going to lower the modulation I'm climbing to fast keep the pump speed where it's at.

Or you can have a third party control do it and fiddle with creating head to make an ecm do what you want.

keyote

Gordy
Thank you for clarifying the ramp control.One issue down.Any thought on flow appreciated.
Regarding you agreement with hot rod Im confused or you two are Im not contemplating buying an interface because the issue isnt the ecm needing PWM and the boiler not having it. The issue is two fold first Lochinvar doesnt even know what an ecm is they dont want any VS pump controlled by boiler without P/S and dont/cant explain why so the choice is really P/S or not. If i understand correctly the pump doesnt really need any control but an on off signal which both the boiler and the zone control can do its software will do its Dt thing on its own.
Now where i may be all wet is getting how much it might help to have the boiler control the pump. But i would think that threshold has to overcome the two pump P/S hurdle and the ecm 505 less energy hurdle is that likely?

Gordy

Good lord........

keyote

Gordy I have re read those pages, not sure i thoroughly understand but think i grokked something i didnt before.
First page 39 is what? recommended primary pumps that are not VS?
I have seen several multispeed pumps that have nice curves some evn ecm, but it seemed to me you had to manually pick a speed curve and my parameters throughout the range crosses their different speed curves. Im .5 gpm/ 1.8 head for one zone on 65 degree day all the way up to 7.6 gpm /8.2 system head [and i think at that flow i must add 2' head for the boiler].for all four zone on design day and i might expand the system one day or find the load was off a bit.

I see what they seem to be suggesting on page 56 is a bit more complex than i first thought, if i read correctly they are saying not just one but two expensive VS pumps one P one S and they are to be wired together and both must be 0-10 volts. its possible there would be no reason these couldn't be substituted for ecms if using P/S and the 0-10v interfaces were used, but you would need ecms with the right curves that did not have software for DT/DP and i think a curve starting at 0/0 for the system pump would be ideal.
Look I get this is crazy, you got this really well made boiler and sophisticated controls with a million features, i really want to use them too, but i think problem is for this size boiler you need different features not major changes but tweaked and instead they have just used what works on their huge boilers where two VS pumps is better than no vs pumps and ecms that size are two grand.

But is all lost if we have solved the flow and mis anticipation problem Hat hadf? If I can pump through with a dt ecm is that not ok or is there something about dt pumping you object to that i dont undestand?

I too think that if it were possible, that boilers brain could manage two ideal ecm pumps magnificently in fact it ought to do it with one ecm, but it cant yet maybe an upgrade later?For now the option they offer id two VS with p/s And i dont see how thats better. but im not a plumber or engineer or electrician
We have looked at my modulation and with the KHN85 im in the 10 - 33% range ideal right? and my water temps and dt are ideal for the condensing right? so we are down to saving electricity while making sure it actually operates without problems.
i actually am hopeful KHN will upgrade and am thinking the premium over htp is worth it even without the upgrade for other features the robust controls offer

Gordy

First of all page 39 refers to what the boiler needs to be happy at low fire, and high fire. Then a variable speed circulator that will communicate with the on board smart control.

When you can understand that, the need for P/S becomes more in the hands of a competent person who understands pump curves, and system curves fluently enough to know the boiler will get those limits any time when the system is running.

Then they can determine whether or not they need p/s even though the manual recommends it. The gentlemen on the help line have no idea of your expertise. I'm sure there is a flow chart that directs them to pipe p/s when in doubt.

Those max, and min flow rates at low, and high fire are key information in helping make that determination.

Many successful direct pipes with one pump on here by the competent.

The boiler controls decide what the ODR curve is based on programming, the modulation, etc, etc. it's the brains of the system.

The boiler needs to tell the circulator what to do not the circulator make the boiler do what it wants.

keyote

THIS IS STUPID RIGHT? its someones brilliant idea to preheat the indirects potable before it goes into the tank while chilling the indirects return loop for condensing.I get the small picture logic but ... or am i the idiot. better to slow the loop down and not waste heat no

As an additional idea

Here is a diagram I developed for a specific project using a condensing boiler with an indirect but I added a brazed plate heat exchanger in the mix.



If you follow the diagram, the way this works is, the entering cold water (50F) is diverted to the brazed plate exchanger (BPX) cold side to pre-heat the water to the tank.



The hot side of the BPX receives returning boiler water from the indirect, diverted from the boiler return. This wrings out another 10 to 15 degrees, depending on the selection of the BPX and increases condensing.

Gordy

Your trying to crack a safe with the combination laying on top of it by trying to open a closet door in another room.

hot_rod

Gordy said:

Your trying to crack a safe with the combination laying on top of it by trying to open a closet door in another room.

Great analogy!

Not sure who at Lochinvar you are talking with? Customer service?
I assure you the R&D engineers in the lab understand all this, it,s not easy getting to them, even with the passcode

keyote

Which part Gordy ? I really worry I when i find im not in synch with you or rather running trying to catch up.
The heat exchanger above was a joke, the indirect as a buffer from yesterday was a desperate attempt to avoid again resorting to having to buy a buffer even after a 10-1 modcon upgrade, But you and Hat assured me i had no worrys about minimum flow because pump cant pump less than minimum flow under those low head conditions that come with low lowds.
[though i still dont know where the rest of the gpm will go] And if i must use one zone for the whole house i will but we think smart control has some tricks to avoid this.

Admittedly the recent indirect idea has intrigued me and id love to play around with it for fun, but its not needed so not being considered.

This whole ecm pump / VS pump, p/s or not thing is simple, I see absolutely no reason to run p/s and two very expensive VS pumps if i dont have a minimum flow problem that would prevent me from using one ecm without p/s, or even that complexity and expense aside, there's an efficiency advantage boiler control would impart that would exceed the efficiency of one ecm and less pipe. given that my modulation bands and condensing bands will be so good its down to electricity

Correct me please if Im wrong I thought you agreed there is a simple way to use the vt2218 controlling itself and dt, and the boiler controlling itself and water temp without p/s.

It wouldn't be the first time i wasn't hearing what was being said. its difficult because whats said is often conditional on variables and the conversation drifts. And cause im a certain type of person we are all familiar with. Gordy no one has been as patient, devoted as much time, and demonstrated as much competency [and their is much competency here] than yourself so if im not in agreement with you Im either misunderstanding or asking for clarification [and occasionally going off on a wild tangent].

Brewbeer

Some more comments, which come from observing my system: when I have a design day, my SWT is about 125 and RWT is about 116. On a mild day, SWT might be 105, and RWT 102. Point being that the system delta decreases as the heat load decreases, at least on my system which is running a 2218 on its lowest setting (which is a measly 9 watts).

keyote

Brewbeer thats very interesting to me i dont have any modcom experience to compare how my system might operate both from the system and near boiler piping perspective. Can you describe your system more, thats the pump i want to use what boiler are you using and are you P/S or straight through piped ?
My loop cad design day 17 degrees, is giving me a SWT of 127 at DT15 and on a 65 degree day its giving me SWT of 91, I originally designed around DT10 but my head/flow was too high to get into the VT2218 curve and gordy suggested i rework some loops and widen the DT which worked. Loopcad only allowed DT in 5 degree increments but by switching between DT 10/15 i can see i can do DT 12.5 just fine.Then i noticed individual loops RWT were all over the place whicj i have to learn why i think its telling me I have to balance the flow meters.So comparisoms are encouraging.
one of my issues in fact what got me into that indirect idea is on warm days my flows are really low as well as loads and i worried i might get lock outs,Like Hatteras was getting, i wonder your system is getting to much heat and to little flow to get rid of it and it cant keep the DT wide enough its good to know the pump keeps trying.

Gordy

There you have it. Everyone caving Thier head in about the emitter delta. Trying to force it. Some times it can be done with design it's been done other times no. Who cares I mean really. It's a design parameter meant to be achieved at design conditions.



You asked what delta radiant floors are designed around. We said 10. That does not mean if it is 5-15 the world ends or the system wont deliver.

Mass makes the delta more stable. More so the mass of the emitter that's the business end. Pass me another beer brew..... I mean @Brewbeer.

Brewbeer

I'm using a Lochinvar WHN055. Three pumps: system pump is the 2218 set on low, boiler is pump is Grundfos 15-58 set on low, DHW pump is a Bell and Gossett ecocirc 19-14 set on speed 4. Boiler Buddy 30 gallon four pipe buffer tank. Emitters are 128 feet of fin tube baseboard piped in 1 inch and 3/4 inch copper split loops, three zones feeding a three level house, each level is one zone. 2,000 sq.ft. ~30,000 BTU design at 0F.

keyote

Oh Hotrod no doubt! this looks to me like a really excellent machine I want to buy it. Someone knows what they are doing at Lochinvar and its great they are american made , and in fairness they did use the term proprietary.
But I talked with two of the guys you get when asking for tech help. Both sounded like pretty much their job is to re back the manual not expand on it at all. One finally suggested that their were marketing guys that were alleged to be engineers, the first marketing guy david george seemed fairly knowledgeable about hydronics and was the most helpful, he said the KHN wasnt his deal and Dan Reddick was worth talking to, I didnt find dan very helpful. I planned my call and am sure they thought i was an experienced installer or designer not that if they do know their **** they could not have flushed me asking the right questions but i kept it circumspect and threw in some choice phrases.
But that said Im going to stand by what i said the issue of PWM output is as easy as any voltage transformer, pump or boiler side. ECM pumps are fairly decently available whats missing is something to do with having the boiler control a pump without P/S because they wont even approve it for a regular VS pump. My guess is with two pumps you have two gears and can dampen and amplify as need be but with one youre on a unicycle.
That said for those who are fine with P/S whether they need it or not their caution is not against ecms per se just against non P/S with variable. so go ahead and use two ecm w p/s


Gordy got me to re read the manual pg 56 and it looks to me like what they are saying is you need two variable speed pumps the boiler and the system and they are connected together.

Variable speed system pump
If a variable speed pump is used in the primary loop, and a
0-10V signal is available from the pump speed control, this
signal can be used by the SMART SYSTEM control to anticipate
changes in the building heat load. By connecting this 0 - 10V
signal to the 0 - 10V SYS PUMP IN terminals, the boiler (or
cascade) can modulate up and down as the primary flow
increases and decreases.



Boiler pump speed output
This 0 - 10V output is available to control the speed of a variable
speed boiler pump. The SMART SYSTEM control will vary
the speed of this pump in order to maintain a minimum T
across the heat exchanger, as well as prevent high limit lockouts
when the flow in the primary loop is extremely low. Note: This
feature is to be used with Primary Secondary Piping systems
only. A system supply sensor must be installed. Connect this
output to the 0 - 10V input on the boiler pump speed control.

keyote

Gordy I wasnt worried about Dt being off a bit i just didnt understand how its controlled at all without a dt pump which hes using and i was woried about why my loopcad was showing a third of the loops i thought set at 15 coming back as high as dt56 i hope its to do with pre balancing and the designs not junk. I think they set a water temp that will work after you balance but show you what going to happen if you dont balance. otherwise i dont get how the temp and dt are not meaningless

hot_rod

keyote said:

Oh Hotrod no doubt! this looks to me like a really excellent machine I want to buy it. Someone knows what they are doing at Lochinvar and its great they are american made , and in fairness they did use the term proprietary.
But I talked with two of the guys you get when asking for tech help. Both sounded like pretty much their job is to re back the manual not expand on it at all. One finally suggested that their were marketing guys that were alleged to be engineers, the first marketing guy david george seemed fairly knowledgeable about hydronics and was the most helpful, he said the KHN wasnt his deal and Dan Reddick was worth talking to, I didnt find dan very helpful. I planned my call and am sure they thought i was an experienced installer or designer not that if they do know their **** they could not have flushed me asking the right questions but i kept it circumspect and threw in some choice phrases.
But that said Im going to stand by what i said the issue of PWM output is as easy as any voltage transformer, pump or boiler side. ECM pumps are fairly decently available whats missing is something to do with having the boiler control a pump without P/S because they wont even approve it for a regular VS pump. My guess is with two pumps you have two gears and can dampen and amplify as need be but with one youre on a unicycle.
That said for those who are fine with P/S whether they need it or not their caution is not against ecms per se just against non P/S with variable. so go ahead and use two ecm w p/s


Gordy got me to re read the manual pg 56 and it looks to me like what they are saying is you need two variable speed pumps the boiler and the system and they are connected together.

Variable speed system pump
If a variable speed pump is used in the primary loop, and a
0-10V signal is available from the pump speed control, this
signal can be used by the SMART SYSTEM control to anticipate
changes in the building heat load. By connecting this 0 - 10V
signal to the 0 - 10V SYS PUMP IN terminals, the boiler (or
cascade) can modulate up and down as the primary flow
increases and decreases.



Boiler pump speed output
This 0 - 10V output is available to control the speed of a variable
speed boiler pump. The SMART SYSTEM control will vary
the speed of this pump in order to maintain a minimum T
across the heat exchanger, as well as prevent high limit lockouts
when the flow in the primary loop is extremely low. Note: This
feature is to be used with Primary Secondary Piping systems
only. A system supply sensor must be installed. Connect this
output to the 0 - 10V input on the boiler pump speed control.

I don't know why there isn't faster acceptance of the PWM logic, it has many advantages over the "old school" analog 0-10 and 4-20ma.

It makes it tougher when some stuff is digital and others analog. Our solar controllers are PWM and fairly inexpensive, tekmar has been PWM for many years. Good question for the product development guys.

Gordy

Now there is a service manual for the KHN. Read it.

keyote

Gordy you mean other than this 'service and installation "manual ?

I dont know hat, never wired a boiler but i read it as two pumps, they call the "boiler pump in the primary loop" and the system pump that is connected to its inputs. I missed it the first couple times maybe i still got it wrong but if it that i think they would both be vs

keyote

Brewbeer how are you controlling your pumps
Each zone is 30kbtuhr ? so youre using the buffer for two zone calls? or the whole load is 30 k and buffers mainly hydraulic separator

Brewbeer

Total building load is 32kbtu/hr, three zones: 12 kbtu, 12kbtu, and 8 kbtu controlled with zone valves. Boiler pump moves heat from boiler into buffer, system pump moves heat from buffer to zones. Buffer is the air removal and hydraulic separator.

Gordy

keyote said:

Gordy you mean other than this 'service and installation "manual ?

I dont know hat, never wired a boiler but i read it as two pumps, they call the "boiler pump in the primary loop" and the system pump that is connected to its inputs. I missed it the first couple times maybe i still got it wrong but if it that i think they would both be vs

Yes there is the I/O manual, and service manual.

keyote

Thanks I asked them three times if there was anything more besides the install manual and videos.Ill study this.

hot_rod

All the manuals are on the Lochinvar website, plenty of documentation
http://lochinvar.com/_linefiles/KH-I-O_Rev C_100267332_2000508039.pdf

keyote

brew beer just curious why the 30 gallon bb i agree as air removers and separators buffers are neat though i wonder about standby loss if not really needed for buffering were you worried about you small zone, wouldn't the 18 gallon have done the job

keyote

Gordy BTW I notice they show pumping into the boiler Im guessing they want to maintain maximum pressure through the boiler but it doesnt have much loss and that makes it not pumping away any thoughts

keyote

Thanks hot rod

hot_rod

In talking with my son Max about the interface between boiler and pump. It seems the the best way is to run the system with the building automation as the control.
They had issues with the larger boilers and the Magna, as a single pumped system, until they had the ability for the pump to communicate back to the system. It wasn't enough for the boiler to drive the pump, the "system" wanted to communicate back to the boiler via the pump, so to speak. Once all three could communicate back and forth, things simmered down.

I'm not a control expert, maybe it takes a PWM signal to be able to have that 3 way communication, instead of just a 0-10 from boiler to pump?

I believe the Magna control is capable, but that would be a $$ control addition to an Alpa price, and size circ.

So it sounds like it is hit or miss as far as IF a single pumped system, will always work properly. I suspect that is true with the DT pumps that have their own control, sometimes they work fine, others not.

What does work is putting P/S in the middle and dual pumping.

keyote

THANKS FOR PASSING THAT ON THE ALPHAS CURVE DOESNT WORK ITS THE VT2218 CURVE THAT IS BOTH LOW AND HIGH ENOUGH FOR MY SYSTEM.i AM NOT SURE IF YOU CAN LOCK IT OUT OF DT AND KEEP THAT CURVE TWO ECM PUMPS WOULD BE EFFICIENT AND THE BOILER ONE COULD BE A SMALLER ECM.i KNOW THE VT2218 IS CONTROLLABLE WITH TACO ZONE CONTROLLER YET I DONT THINK IT PUTS OUT PWM ILL HAVE TO LOOK INTO BMS, HAVNT HAD TIME TO READ THE SERVICE MANUAL YET,
MY GUESS [THATS A LAUGH IM NOT EVEN A PLUMBER] IS TROUBLE STARTS IF YOU CAN NOT GUARANTEE SUFFICIENT FLOW BECAUSE OF SMALL LOADS OR CERTAIN PUMP CURVES.HAT SAYS ITS IMPOSSIBLE FOR THE 2218 TO PUMP LESS THAN 1.6 GPM, AT dT 10-15 8500BTU 90 DEGREE WATER I DID THE REVERSE MATH AND HE SEEMS TO BE CORRECT, THOUGH I DONT UNDERSTAND TWO THINGS ONE IS DOES THE PUMP HAVE A MINIMUM SPEED IT CANT PUMP LESS THAN WHICH I THINK IS TRUE AND THATS THE BOTTOM CURVE, THE OTHER IS IF IT REALLY STARTING TO PUMP THAT HARD BUT MY LOWST ZONE ON A 65 DEGREE DAY ONLY NEEDS 1/2 GPM WHER THE EXTRA WATER GO AM I SUPPOSED TO PUT IN A BY PASS LOOP TO KEEP IT DIVERTED BACK TO BOILER?

Gordy

You have to start thinking about your system side. Get it to conform to page 39 specs.

Read the service manual there are pictures of input peripheral devices, and output peripheral devices.

Or you save the head bangin, and focus on an htp product that is a buffer boiler, and dhw all in one......

However ther are plenty of control options on the Khn to make it sing IF you become intement with them , and your design......

Gordy

Hot rod are these commercial, or residential applications? A little detail on why a direct piped had issues.

Brewbeer

keyote said:

brew beer just curious why the 30 gallon bb i agree as air removers and separators buffers are neat though i wonder about standby loss if not really needed for buffering were you worried about you small zone, wouldn't the 18 gallon have done the job

Definitely needed for buffering. Over 40 degrees outside the boiler always hits the ODR high limit before heat call is ended since usually only zone ( the bottom floor zone) is running. Price difference between the 18 and 30 is insignificant and the larger buffer reduces the boiler cycling by almost 1/2.