Wiring Lochinvar Knight + single Grundfos Alpha

djohn

Questions coming from a guy that used nothing but pump zoned systems, so excuse my ignorance. First time for Knight too.



It's piped pretty much like "single temp - full flow with zone valves" diagram per Lochinvar literature. Single pump, no P/S piping, no bypass pressure valve. Alpha is plugin type. Currently have 1 zone piped in, will end up with 3 zones operated by zone valves (sentrys)



I have not installed Knight's system supply temp sensor. It's not clear from the manual whether it's required only with P/S piping to monitor primary loop temp. I can still do it though.



So questions are:

1. How to wire single Alpha with Knight?

2. Is supply temp sensor required or useful without P/S piping?

3. Do I leave zone sentry in open position for now (until remaining zones are in) or do I wire it in. If so, how?

ced48

Wire to Boiler Pump-

not system pump, and no system sensor-Run at set speed, or you will screw with modulation-

djohn

conflict

I was convinced that delta-P pump would not fight the mod-con. Delta-T pump like Bumblebee - maybe. Are you sure about it? Anyone else?



Alphas curves pretty much match my design loads with 1, 2 and 3 zones calling, so running it at set speed would be a huge waste.



Using Alpha as boiler pump makes sense since that's what Lochinvar shows on diagram too. Question is, is Knight smart enough on it's own to delay the fire until the pump is running AND at least one of the zone valves is open?



Any recent information about cutting the plug on Alpha? Warranty void or not? I can either cut it and wire everything inside Lochinvar or leave it and add an external box.

Steve Whitbeck

piping

Unless this is the WHN fire tube boiler You need to pipe it primary/secondary.

Even with the fire tube model it is recommended that You install a pressure differential valve at the end of the manifold if it isn't piped primary/secondary.

The only time either boiler can be piped the same as a cast iron boiler is IF there are no isolating valves or pumps. It has to be one big zone. ( Or if the smallest zone can flow enough water to satisfy the GPM needs of the boiler all by itself.)

If you pipe a high efficient boiler in a manner that doesn't maintain a minimum flow through the boiler YOU WILL drastically shorten the life of the boiler.

unclejohn

Don't know

Much about the Knight but would highly recommend P/S and a buffer tank. Also leave the plug on the pump and wire a receptacle to the boiler.

djohn

piping

It is WHN110 and straight piping is per Lochinvar's diagram.

No DPV because it's variable speed pump.

Steve Whitbeck

Piping

They show a pressure differential valve. Install it - it will be needed.

Or for about the same cost install it primary/secondary.

The recommended installation method is primary/secondary for a reason.

djohn

P/S

DPV is redundant with variable speed circulator. In another thread I was advised against it in this system, as a waste of $. Lochinvar's diagram shows it because pump that it ships with, is a plain old single speed Grundfos.



P/S piping is not the same cost, since it requires more material and additional pump, which also adds running costs.



Goal of this install was to create a single pump system, which is still doable - to my best belief.

Zman

Answers

1. Wire the alpha to boiler pump terminals. Cut the cord end off and wire it direct. Set the alpha to one of the constant pressure modes. Don't put it in "auto adapt" for this application. I would find one that gets you the delta t you are looking for. 20 works well for most systems.Just try the 3 settings until you find one that gets the right delta t.



2. You do not need or want the sensor.



3. Control the zone valves with a zone control relay.The Taco  ZVC404-4 is straight forward.

For now you could bipass the valve and wire the t-stat to the boiler. Eventually you will need a controller.



Carl

djohn

carl!

Finally some music to my ears



1. One thing I am not completely sure is auto-adapt. Can you elaborate why it wouldn't work?



Everything else you wrote makes total sense for me. I will try to get the Delta-T that works. Since right now the only zone I have is in slab, I might shoot for something closer to 10F.



After all zones are in, I will probably have to tweak delta-T's on slab vs joist trak using manifold itself, by restricting flow.



2. That's what I was thinking too.



3. And I was just looking at Taco website and ZVC's

I was debating how to make the each of 3 sentrys open and that's gotta be it. With 3 zones, 1 extra spot on the control board is exactly what I did with Taco pump switching relay. Just in case, but also never had 1 fry on me.



One other idea I had was to get one normally open sentry and that zone would pretty much act as dump zone. I was way overthinking that, since boiler will not fire until pump is running. And pump will be running at constant pressure, adjusting to 1-2-3 sentrys open.



4. New question: Should I wire anything through WHN110's zone terminals, to achieve different temps? From what I understand, it can be programmed to run lower temp (and I might not even need that, on slab vs joist trak) when slab zone is calling.



Thank you so far and I will appreciate any additional suggestions.

Eastman

zones

What guarantees the sentry valves are open when a call for heat comes in?

djohn

protection

With ZVC, isn't the case that the boiler won't fire, unless zone valve is open?

And since we are touching this subject, wouldn't ZVC-EXP be better than regular ZVC?



Or you are talking about possible malfunction?



Hint towards using one normally open sentry?



And finally, doesn't WHN110 have built in flow switch? Malfunctioning valve still closed, pump running but no flow = no fire?



Thanks for brainstorming this with me and picking on possible weaknesses of this design.

Eastman

I don't think it checks the flow before firing.

I really doubt the boiler is that sophisticated.

Zman

Auto Adapt

The auto adapt will reset itself every time it powers down. It has to learn all over again. I have never had much luck with auto adapt and radiant anyway. Radiant loops will run well on cp2 or cp3.10 degrees  would be a good target on radiant.



You can use the zone terminals and get the temp you want when only one type of zone is calling. You would have to jumper the end switch terminals on the ZVC and run the 2nd temp zone valve end switches directly to the boiler.



I don't think proving flow is a huge issue. The boiler will lock out if it detects anything irregular. You have to remember, it is always looking at delta t and rate of rise. A pretty smart controller.



How big are your radiant zones?. How long and how many loops? If the zones are too small,or to long you may run into minimum flow issues. I have only done direct piping (non ps) on baseboard systems. It might be worth a call to Lochivar. I see a minimum flow rate fire full output in the manual. The may have a minimum flow rate for you application.



Carl

Dave H_2

Zone Sentries,

The Zone Sentries have a dedicated end switch. This contact closes when the valve is open.

When wired to a ZVC controller, the endswitch to the boiler won't close until there is a thermostat call AND the Zone Sentry endswitch closes.



Dave H.

ced48

On Second Thought-

I don't see how this system will work without combining all zones, or going p/s. You will never be able to get the proper flow depending on how many zones are calling for heat.

djohn

zones

My zones are:

- 6 loop slab

- projected 7 loop joist trak

- projected 8 loop joist trak

All 250ft 1/2" pex, piped through 3 Caleffi Twistflow manifolds. I posted head calculation in another thread here and it's really low - around 5ft (1.5ft on the boiler and 3.5 on the system).



Alpha's speed curves seem to match my loads with 1, 2 and 3 zones calling for heat.

Should be around 3gpm per zone, up to 10gpm per entire system at full load. Not sure what Alpha will do exactly though.



Any idea what them minimum flow numbers are? Trying to research it now.

Thanks for explanation on autoadapt.

djohn

flow switch

WHN110 has flow switch terminals and they are factory jumpered. Flow switch could be added though, but the SMARTSYSTEM likely has other means to protect the boiler: valve closed -> pump not running -> boiler not firing,

djohn

sentries

Good info on zone sentries! Encouraging

ced48

Why Do Posts

get posted out of order? Sometimes this makes the poster look a bit, shall we say, slow-

Zman

Posts

Ced48, If someone clicks reply on a post rather than the whole thread (at the bottom) it puts it out of order.



Here is the spec on the alpha http://us.grundfos.com/content/dam/GPU/Products/ALPHA/ALPHA%20brochure.pdf

It looks like CP3 will give you 12feet of head up to 6 gpm. It looks like that would be a little over 4 gpm on your smallest zone.

I think you will be fine as you are piping it, I just haven't tried it.

Please let us know how the boiler responds.

Carl

Jean-David Beyer

Why Do Posts get posted out of order?

I think there are two issues here, at least as I observe them.



1.) Some people want all posts in chronological order. To get that, you have to press the "Post A Reply To This Thread" button at the top of the thread.



2.) Some people want a post that responds to an existing post to be immediately after the post being replied to (and indented). To do that, you have to press the "Reply" button next to the post being replied to. This usually works, but once in a while, it goes at the bottom of the thread anyway.



So there is the issue of what order is the correct one, and there is the question of whether there is a bug in the reply mechanism. Also, once in a great while (less than once a month) sometimes a post just disappears.

Steve Whitbeck

Flow

The problem I see is that you will not have the proper flow for the boiler.

The reason for the PDV is NOT to maintain a given ft of head in the supply manifold BUT to maintain a given flow through the boiler. Yes you can run that boiler as if it were a cast iron boiler BUT should you, NO - it will shorten it's life.

The install manual shows that you can use a concentric vent termination but should you --- NO - NO - NO - NEVER

djohn

curves

Assuming head will be closer to 6ft (1.5ft boiler, 3.5ft tubing, ~1ft boiler piping), wouldn't constant pressure Ih be closest to what system will need, since it provides up to 14gpm at 6gpm?



Head should be pretty much the same with 1-2-3 zones calling.



I wondered about power draw too and here are my conclusions:

Since WHN110 handles 10gpm at 20F delta-T, with 10gpm spread throughout 3 zones - let's say 3.33gpm each, with 8W-45W Alpha's power draw (assuming 45W at 14gpm), Alpha should be drawing:

~17W with 1 zone open

~ 25.5W with 2 zones open

~ 34.5W with 3 zones open

djohn

dpv

DPV role isn't to maintain the flow through the boiler, but to limit the pressure. It's used with single speed circulators pumping through valve operated zones. If let's say 2 of 3 zones are closed and circulator still pumps at the same speed, pressure has to go somewhere and DPV lets it go back to return piping.



As others have mentioned (and what also Siggy mentions in his book), DPV has no place in the piping when variable speed circulator is used. It adjusts the speed (and pressure) to 1-2-3 zone valves opening and eliminates overpressurizing of the single zone.

Steve Whitbeck

DPV

I KNOW what a differential pressure valve can be used for.

BUT in this case it is there to ensure proper flow for the boiler. NOT to limit the head pressure in the supply manifold.

If only ONE zone is running the DPV will be open - bypassing water back to the boiler. That way no matter the number of zones running the boiler always gets at least minimum flow.

If you are trying to build the lowest installation cost, lowest operating cost system go for it.

When the boiler takes a dump - Did you save anything?

djohn

dump

And boiler would take a dump WHY exactly? (I see you like using caps)

djohn

zvc exp or non exp

So Carl mentioned Taco ZVC404-4, which is a smart choice over 3 zone version, in case one of the zone circuits fails.



My question would be - is there anything in Taco ZVC404-EXP-4 that would make me want to use it over non-EXP version. I know I won't be expanding my zones or adding cards. Taco docs are somewhat conflicting and lacking in detailed info. Big wiring guide shows EXP diagram with some jumpers. Just wondering if they are useful in my situation.

Zman

EXP

I am not thinking you need the extra features of the exp.

I like higher flows through the tubing than you are calculating. I would like to see more like .7 to .8 gpm per loop. This will put you in the higher head range.

Higher flow rates will give you more even heat and better flow through the boiler.

Carl

djohn

right

I think you are right. Finally found a newer revision of exp diagrams and it was not on Taco website. http://media.blueridgecompany.com/documents/TacoZVC404-EXP-4.pdf



Other than maybe pump exercise, there is nothing I really need there.



I will play with Alpha settings for sure. 0.7gpm per loop would result with closer to 10F delta-T, which might be good after all. Still playing with 1st and 2nd floor layout and I might be ending up with more loops that I originally planned. More like 8 and 9 (on the top of existing 6), which would add up to 23 loops and 0.6gpm per loop at full load.

Steve Whitbeck

DUMP

I use caps to make sure that the reader understands it is important.

Dump means leaks.

Not having the proper recommended flow for the boiler will cause the boiler to have much greater heat cycles and that stresses the boiler and shortens it's life.

The only way I would use a VS pump is if it is controlled by the boiler via a 0 to 10 V control signal and an open loop that is capable of flowing the minimum flow that the boiler needs.

I purchased a HTP Elite FT 55 for my basement and I plan on using a boiler pump in that manor.

Mine will be piped P/S.

djohn

elite

Elite just like Knight adds just tiny amount of head and just like Knight doesn't require P/S piping. Unless you are running some more complicated, multi temp, multi zone system, P/S piping has no advantages over straight piping.

Gordy

P/S advantage

Maybe I missed something, but are you not zoning, and if so if only any one of the future 3zones are calling will that zone alone provide the min. Flow rate the boiler needs? If not then you better do P/S piping Steve covered that in his first post.. This is also noted in the piping diagram for the knight.

djohn

zoning

Yes I am zoning, but I am doing so just because it's 3 different levels of the home. It's going to be single temp system.



Variable speed pump should have no problems adjusting to 1-2-3 zones calling. Single zone should still have flow around 3-4gpm.

Steve Whitbeck

SO

SO you think that 3 - 4 GPM is OK for a 110,000 BTU fire tube boiler???

ANY high efficient stainless steel boiler WILL be damaged in the long run by firing at or below minimum GPM.

You can only use a variable speed pump on the boiler loop ( system pump if one BIG loop ) IF the pump speed is controlled by the boiler via 0 - 10 volt input.

The pump speed increases as the boiler BTU rises. As the BTU's go up so does the pump speed.

I don't care how many zones are calling,  what matters is the flow through the boiler.

You keep thinking that you can slow the pump down as the zone demand drops.

With P/S piping that would be fine, and the boiler pump could be set to slow down also but it would be controlled only by the boiler.

With your method what happens when 1 zone calls that has been off all day causing very cold return temp. The boiler won't know that only one zone is calling. It will see the cold return temp and go to full fire at minimum water flow.

djohn

minimum gpm

1. What is minimum gpm for WHN110? You keep saying that, but what is the number?

2. Why would it fire at full 110K BTU input, if it can modulate down to 22K BTU?

3. What exactly would be damaged caused by? High temp? WHN110 has both return and supply temp sensors and monitors delta-T continuously.

4. All zones will have slab sensors and I don't see temp going low enough to boiler going full throttle on 1 zone and self destroying itself. That's crazy even without floor sensor.

5. What is the point of $500 VS 0-10V primary pump in single temp system?

Steve Whitbeck

You are not listening

GOOD LUCK

GO FOR IT

don't blame the boiler when it dies early.

Even a cast iron boiler SHOULD not be fired with no water flow.

Minimum flow is 1 GPM for each 10,000 BTU of firing rate for 20* Delta T.

Your pumping plan will not supply minimum flow if only one zone is calling.

You can't understand how the boiler could full rate fire if only one zone is calling.

Because the low return temp of a cold zone starting up will cause the boiler to go to full fire. IF you want to install this system yourself YOU should already know these facts.

YOUR piping system will damage the boiler.

P/S piping will only cost in parts less than $ 150.00

Piping the boiler your way will shorten it's life.

And last time I bought a DPV I think it was more than that.

djohn

questio

I asked you a simple question which you don't know the answer for (nor do I) but you keep stating that low flow will destroy my boiler, like it doesn't have any type of temp protection. What low flow? How many gpms at what pressure, exactly? What will destroy my boiler?



What will happen is, in case there is too high of the output temp (uncontrolled, over set temp), boiler will lock out and I will consider my options. At this point though I expect it to just work.



Good luck with your ventures too.

Gordy

6/35

You need minimum 6 gpm at 35* delta t on the boiler loop.. That's minimum. Read the manual it's in there.



Your 1/2 or less the minimum flow rate for a 35* delta on the boiler loop IF that's the delta your are going to use. It goes up to 10 min. At a 20 delta. Now will you listen, and pressure why is that a topic?



What makes you think you will always be at minimum modulation IF that is the case your boiler is to big.



You could get away with direct piping IF the system required a flow rate between 6 and 10 gpm. You don't have that requirement. It's your warranty, and Loch will figure it out when your HX over heats, and craps out, or you will be back wondering why the boiler locks out.

Steve Whitbeck

You are not listening

I did answer your questions. You don't like the answers.

Let me explain it better. Heat cycling is what happens each time the burner fires.

With no or low water flow the boiler will heat up very quickly causing high heat expansion stress.

Have you ever cleaned a Gianoni ( spelling ) heat exchanger?

Ever notice how the tubes go up and down like waves. They are not flat like when the boiler was new. ( NONE of the ones I have installed did this )

This is caused by overheating and heat stress.

Water pressure is not important as long as it is at least 12 PSI.

Since we are not talking high pressure boilers the water pressure in regards to GPM is not relevant.

The boiler will only start to modulate down as it gets near the lower limit setting.

It will tend to overshoot and hit the manual reset limit.

I have been installing boilers since I was 15 YOA - I am now 56.

I have a B2 Michigan state boiler license - I passed first try. ( I never had a B1 )

I have been installing high efficient boilers for about 14 years.

If you call the HTP distributor for west Michigan they will likely give you my number for a recommended service provider.

There are VERY knowledgeable people here making suggestions to you but YOU are not listening.

IF you have your mind set on doing it your way - WHY did you come here? 

djohn

gpms

Gordy and Steve,



I know you are trying to help and critique my design and save me from a costly blunder.



Looking at Gordy's numbers, I am pretty sure you are correct on the numbers themselves, but they are not minimum flow numbers, but rather a design or capacity numbers. Nowhere could I find "minimum flow" wording. But I could find capacity numbers stating Knight handling 10gpm at 20F. Which means maximum flow numbers at given delta-T. If these were minimum numbers, it would handle 20gpm at 15F.



Per manual, WHN110 is capable of achieving 20F delta-T on 10gpm flow, at full fire. And 35F delta-T on 6gpm flow, at full fire.



Now, assuming it can tune down 5:1, at minimum fire rate (22K BTU input), it should achieve 20F delta T at 2GPM. and 35 delta-T at 1.2GPM. 10F delta T probably at as low as 1GPM.



I never said it will always fire at 22kBTU when one zone calls. But Alpha should always maintain a proper pressure and flow. Alpha is a completely new animal for me, but with 7 different settings I bet I will find a proper curve.



BTW, this is firetube and not Gianonni heat exchanger and yes, I have cleaned them. NTI's were so restrictive, that they needed a P/S piping and primary pump that can pull out 40ft of head. Knight restriction is a whopping 1.5ft of head.



Why I came here? To be asked hard questions, like yours and get good advice (some of yours too from SWEI, HotRod, Zman. And I am making a big leap of faith here and some new learning too as this type of the system is completely new to me (firetube, alpha, no P/S piping) I believe it will work. And if it doesn't, my boiler will lock out and not explode, hopefully.



If you asked me about P/S piping 5 years ago, my response would have been exactly as yours and I would call myself crazy.