Buffer Addition

PeterNH

Hello ,

This a plan i have been working on to add a Boiler Buddy to my system

I think it will work.

However, any suggestions, advice, criticism, approvals etc. are more than welcome. Please.

This not going to be a DIY job. The the local oil guys, who are excellent tradesmen, will be doing the work.  They have never installed a Boiler Buddy before, so i have done this design to help guide the project.

Higher quality view:

<a href="http://home.comcast.net/~k16862/Heat/BB02a.JPG">http://home.comcast.net/~k16862/Heat/BB02a.JPG



.

Thanks,

Peter</a>

Zman

Solar?

What is the solar? Is the buffer tank  also your solar storage. If the boiler fires first thing in the morning it will heat your solar storage and leave you no place to store your heat.

Give some more details on the boiler panels and heat emitters.

PeterNH

No Solar yet...

Hello Zman,

Thanks  for looking.

The solar is a future idea. The buffer is not for solar storage.

The buffer temp will be full ODR by Tekmar

zones:

1 sun porch/plants 40 deg fin tube

2 garage 40 deg fin tube

3 hobby room 50 deg + 70 deg fin tube, over radiated by 100%, 200% when all the lights are on. (model railroad over garage)

4 1 floor house fin tube(will add more)

5 2nd floor house fin tube, over radiated 3-400+ %

6 3 floor house fin tube over radiated by 3-400%

7 front hall 60 deg, fin tube over radiated by 500%

8 1st floor bedroom, fin tube over radiated by 200%

(9-) posible radiant addition to first floor tiled areas, aprox 400 sq ft, under consideration. Taco ivalve or Tekmar



About 3000 sq ft, near super insulated, except the 1st floor.

Typical heat loss on an average cloudy 30 degree day is, 15,000 btu's

Sunny, and 30 about 3-5,000 btu's

-20 aprox 54,000 btu

"design" -3 about 40,000 btu's

No natural gas.





Peter

STEVEusaPA

Some comments...

1. I'm going to need to see a pic of the model railroad. Has nothing to do with the design. Lol

2. What kind of boiler do you have now?

3. Why do you think you need the bypass with the buffer? Does it have something to do with the solar? Hard to make out the components at the bottom of the pic.

4. I don't think you need the air eliminator in the primary loop. If the air gets to there, it could go right into the buffer tank and vent out the top. There' no air elimination in the solar loop, or any easy way to get it out after initial purging.

5. Little concerned with that many zone valves on the supply, but it may be ok with the Alpha.

Looks good, except for control strategy.

Btw what does the existing system look like now?

PeterNH

Real soon now

1. Mostly plywood and foam right now.

However, below, is a buddy's, who owes me about 1000 horsepower hours and a good example of where i'm heading with my layout.



2. About a  20 year old Ultimate 4 section boiler with a Riello.

.50 at 150 lbs aprox .61 gph

Working pretty sweet. It was over drafted for years, but we finally got it corrected and the combustion numbers come in around 85-86%

There is a rumor going around that the Vitorondens might get imported, this year... ??..

If it does, i might have to sell a few thousand rail cars and get one.



3.  Nothing to do with solar.

There will be a lot days/weeks when  80-120 degree buffer tank temps will give all the heat needed. IMO returning 50+ gallons of under 100 degree water, would not be to good for the boiler.



4. The idea was for a "micro bubble" eliminator.  Maybe it is overkill?

I can add air elimination to the solar loop, if it ever happens.



5.There are 8 zones now and everything works with no aparent flow problems.

Most of the time, zones 4 5 and 7 are never open.

EIDIT Correction zones 5 6 and 7



 

6. I have a couple of possible control plans in the works.

One low budget, the other quite costly.

I'll post them after we get the piping finalized.

The biggest  purpose for this plan, besides a short cycling cure, is to get more constant circulation - to increase the comfort factor and any cost saving, that might come from full outdoor reset.

 

The existing system, has the 8 zones on the supply off the boiler and a 007 on the return. Old style stuff, but it works. The existing 40g super stor has it's own 007 pump and loop.



Thanks for your time and thoughts,

Peter

Zman

Looks like

It looks like you are using the 3 way valve with controls to prevent condensation, good. Do all your zone use about the same temp? What is the Btu requirement of your smaller zones(or give a description). What is the minimum BTU out put of your boiler. I am thinking the buffer tank may be a bit large.I would personally figure a minimum boiler cycle at about 10 minutes and design the buffer around that. 

PeterNH

Size

Hello Zman,



Do all your zone use about the same temp?

===========================

They do at this time. Yes.

Pretty sure about adding radiant to the tiled areas on the first floor

so that could change



What is the Btu requirement of your smaller zone

=================================

Zone 1 would be 3-4000 btu's

the new radiant zone would also be about 4,000



 I am thinking the buffer tank may be a bit large

==============================

Agree 40 gallons would be better.

Depending upon how the efficiency is calculated for the boiler, at say 80%

the output would be 66,000 btu's hr

85% would be almost 71,000

using 80%: 66,000 btu's hr: and the 50 gallon Boiler Buddy,

According to the math, It will take take 9.3 minutes to heat the buffer with a 25 degree differentail,  135 to 160

If zone 1 is running it will take, 10 minutes.

Add about 3+/- minutes to these times for the boiler itself to heat up.



Thanks for your time Zman,

Peter

Zman

Sounds Close

The boiler turndown is higher than I would have thought.It is hard to get it exact without all the system volumes.It sounds like 40 or 50 is appropriate. In a perfect world your boiler will fire on a fairly wide differential (145 to 185?)and your tank  will have a tighter one maybe 10 to 20 degrees and based on outdoor reset. Make sure you boiler pump stays on anytime you have a call for heat. If it is controlled by the boiler and the tekmar turns the boiler off, you won't be utilizing the mass of the boiler and its water.

PeterNH

differentials

 

Make sure you boiler pump stays on anytime you have a call for heat. If it is controlled by the boiler and the tekmar turns the boiler off, you won't be utilizing the mass of the boiler and its water.

====================

Agree this is key.

I have a proposed control strategy to deal with this. The pump will be on when the boiler supply is at a higher temperature than the return from the buffer.  This would be run by a differntial controller. It will shut off, if the buffer return is hotter than the boiler supply. This would only be active when there is no call to the boiler. The zone valve bypass around the ESBE valve, is part of this.  I'll post more details on the proposed controls later.

 

 

I'm not sure how the boiler can have a larger differential than the buffer, unless and independent control is used to fire the buffer, rather than the ODR control for the buffer.

But even then the low point would have to be the same, or the buffer could be calling for heat at say 150, but the boiler won't turn on until it drops to 145.

this would then end up forcing the buffer to the same diferential as the boiler.

?



Peter

Zman

Boiler Control

I am heading out on vacation for about a week. I am assuming your mixing valve will be adjusting for outdoor reset. The target water in the tank and the water flowing to the tank from the boiler will mixed to outdoor reset. This temp will have a target and differential.



On the other side The boiler is going to be set up to run with a return no lower that 135 and a supply of say 145 to 185. Because the boiler is returning some of the water back to itself, it can have it's own temp and diff.



If I were trying to get an accurate buffer size, I would calculate the boiler+water and it's delta T and add it to the buffer tank+zone piping and it's delta T. Then I would figure the extra boiler heat not being absorbed by the heat load and go from there.

PeterNH

Time Out

Have a good vacation ZMan.

Catch up with you later.



Peter

scott markle_2

pictures

The boiler buddy is a nicely made insulated steel tank. Unfortunately it's special order and for me uncompetitive. A steel tank should cheaper than an enameled one.



Here's a budget version using the electric element tapings of a 30 gallon.



Good results, wish I had a bypass return device like you show. A new Taco ecm pump is in bata that can do set point modulation, great for injection bridges and possibly bypass loops etc.



Consider a full reset mix on the secondary side. Why go to bing bang land when you can modulate down to 70 deg supply. Buffer is great with full reset injection mixing and fixed fire boilers. Where mico-loading will otherwise cause short cycle.



The tekmar house control series bring this refinement at a more mainstream price point than previous tn4 systems.

PeterNH

Nice Work!

That's some beautiful work Scott

Are you anywhere near Southern New Hampshire?

Anyway.

I was told the threads on a hot water heater are "straight" and can't be connected to normal threaded pipe.

Although i've heard there are work arounds.

How did you do it?



 

 

 I researched the use of a variable speed pump on the bypass line for boiler protecttion.

There is an article by John Siegenthaler, that doess a good ofb of explaining why it doesn't always work. I'll look for the link.

It was also suggested to me, that a large delta T pump would protect the boiler.

Maybe, maybe not. Slowing the flow thru the boiler to a trickle with a 40 degree delta T, imo is not the answer.

So i ended up with the ESBE valve.

Another option would be a Tekmar valve, motor and controller, at two and a half  times the cost.  I have read enough good things about the ESBE to feel confident it will do the job.

I, the other thread, I read about your solution to use the HW sensor on the Tekmar to maintain a minimum lower bufffer temperature. 

That is a brilliant solution!



I you have any time, could you review my plan as far as pump placement, check valve placements and purge abiltiy.

I'll post a larger version later this evening

  

Full reset of the buffer temperature is the plan.

Thanks,

Peter

PeterNH

Link

Pumped bypass limitations:

http://www.pmengineer.com/CDA/Archives/d2d8f85b60398010VgnVCM100000f932a8c0____



Peter

PeterNH

Diagram

Here is a new version of the diagram.

http://home.comcast.net/~k16862/Heat/BB02d.jpg

I tried to make it bigger, but it got fuzzier, so sorry, it's the best that can be done, with the current software.



Peter

scott markle_2

follow up

I posted the wrong shots, no problems with the 1" tank threads. I was concerned too, but had seen it done successfully so decided to follow suit. I did use loctite 55, it comes with Visessmann tanks (they used to provide actual hemp) the product is dispensed like dental floss and has a non messy (dry) impregnated fiber consistency. I used unions because a expected that it might take more than one try, but it didn't.



When I advocate full reset I mean on the secondary side, based on a target that's calculated for the zone of greatest demand. Load matching by temperature modulation instead of just on/off. If you full reset the tank (as opposed to mixing out of it )you will be forced to maintain a fairly narrow differential, and won't be leveraging that volume the way you could. VS injection mixing or 3-way can dial in very precise targets, when everything is right it's great to see how a bunch of different zones can be coaxed into something very close to constant circulation.



My approach not fully realized on the system pictured is to let the buffer swing widely and hold the supply constant (according to load). The Vitrorond will do fine with 115 return at a moderate flow, but since the system side is often mixing down to 85 deg. I could be taking the buffer there too, if I had included added boiler protection. The House control I'm using measures supply temperatures but it's still smart about not sending giant amounts of cool water back to the boiler, it starts slow and ramps up if the mix is achievable without dropping the boiler supply.





I picture something a bit different from the injection loop that siggy is using, I currently have my boiler alpha on fixed speed 2, if I used a variable speed set point controlled pump of equivalent size (Bumble Bee) in a bypass arrangement that fights with the alpha (colliding flow return T). Do you think the BB at full modulation would reduce the flow through the buffer to say .2 gpm on cold start? This might be better than the siggy drawing (for my application) because it would only require both pumps to run simultaneously for a relatively short the warm up period, as oppose two pumps all the time in the injection layout.

PeterNH

BBee

Hello Scott,

Understand on the system side reset. I'll be thinking about it.

I was trying to keep this as simple as possible and that also includes not having a large number of pumps running. Along with thousands in Tekmar controls and thermostats.  But, maybe yes.

.

I've been playing around with a couple of two stage room thermostats.

1st stage just opens the valve and water gravity flows around. Works quite well. Second stage closes the end switch and fires up the circulator and sends the boiler a'stat to the hight limit. The coldest zone will heat down to 45 by gravity on low limit of 120-165. 

All the other zones heat, by gravity down to about 25-30. Of course that includes the added flow when the cold zone turns on the cirulator and heats up the boiler.  It certainy helps a great deal, in the short cycling department. 

   . .

I wish the Taco rep. would have taken you up on your offer to test the BB in the bypass configuration.

You are certainly qualified to handle the particulars.

The BB appears to be a stout pump, for sure. Its hard to tell how much it will overpower the Alpha's return.

For all the trouble of installing it, you might as well just configure a three way ESBE.

  .

I have a different byplass plan that is simalar to your idea with the BBee.

Use a Taco 2 way setpoint iValve on the bypass, with a Alpha, set to the max, behind it.

Put the i valve sensor on the return near the boiler, set it to 115 or so..

When the temp drops the iValve will open, the Alpha will ramp up and bypass water will flow.

Same question remains as to how much it will overpower the boiler pump.

Siggy's article scared me away from it.

Not being a professional plumber, i have to try and get this as close as possible on the first try. Otherwise it can quickly get a bit +++ costly.

In any case, i certainly do enjoy pondering all this out. Rather fun.



Peter

Tim Potter

Progress

How is your project progressing???



Tim

PeterNH

No Hurry

but i can't wait to get it all working.

 



Hi Tim,

Thanks for asking.

Well, the Boiler Buddy is in and down the cellar.

Today, we poured some sand mix to level out the floor where it's going to go.

The wall where the zones are going to be re-plumbed is covered with 3/4"plywood and got a second coat Semi-Gloss white today. Ready to go.

I have a list of the major items i need to submit to the local plumbing supply for pricing tomorrow.

The guys over at the local oil company, that are going to do most of the work, actually got a bit busy with repairs, finally, this winter.

This is going to be a monday afternoon, "mud season" project for fill in work.

Thus i'm getting a reasonably good deal on the hourly rate.

 

I have re-done the design some and the oil guys think it "might" work, so as they get some time and we aquire the major parts thing are ready to proceed.





I'll repost the latest design in a few days.

And see if i can get some "Wall Approval."

I still owe Steve, some pics of the model train room...

The control strategy is still in limbo, between, the ultimate Tekmar plan and a lower cost version.

We also have a plan on how to proceed. Set the Buffer in place.

Pipe the headers to the zone valves/supply side , etc.

Pipe all the new zones etc.

Then work towards the boiler and indirect.

Then set up the new expansion tank and water feed.

As the weather gets warmer, we'll start cutting in unneeded zones and at some point, re-pipe to the boiler and then first, get the hot water working.

Then finsihe everything else while working on the rest of the controls.



Or something like that.

Peter

Tim Potter

I’LL share my experiences with adding a Boiler-Buddy

After my re-plumb, my system looks very much like the picture in your 1st post, but no solar connection and no bypass on the ESBE, both the primary & DHW boiler pumps are 007’s. My BB is an 80gal, I went for that size to maximize the on & off times.



My house, when constructed in 1997, had a cast iron boiler hooked directly into radiant in floor tubing. Over the years the previous owner must have had issues, because they added a 26-99 in series to the 007 pump that the boiler came with, as Mark Eatherton commented, “may as well add more pumps if the system isn’t working well”



Needless to say, the boiler was mostly operating under 140* and condensing (bad), or the tubing was running over 140*(also bad).

The house was either cold or the floors were hot along with the corresponding big swings in room temp.

Thanks to the “WALL” After reading & asking questions, I learned the correct way my system should have been setup from the beginning. I redesigned my system utilizing an 80gal boiler buddy, re-plumbed for injection mixing & ODR using a Weil-Mclain IPC II (very similar to Tekmar 361 Mixing control, just no room sensor). Even though the IPCII/361 has a return sensor & setting to protect the boiler, I added an ESBE Thermic Bypass to protect the boiler, To quote Mark Eatherton again, Its bulletproof, & simple. After the local Boiler man installed it, the boiler settled right in to 140 and above, This allowed me to then turned boiler protection off in the IPC control, so it regulates water temp spot on target as soon as there is a heat call utilizing the residual hot water in the buffer. The only time the boiler fires is when the control is struggling to make set temp with the amount of heat in the buffer. The boiler then runs for a good long burn to recharge the buffer.



After the redesign & re-plumb, the results were amazing, the ESBE keeps the boiler >140*. The buffer keeps the boiler on and off times VERY long, & injection keeps the house temps just perfect.

Our house is 2 story: The walk out Lower level consists of 2 BR’s, 2bath, Family room & utility with the tubing in-Slab. The Main floor consists of Master BR, Master Ba, Living, Dining, Kitchen, w/tube in light weight Gyp. Each area (7) has its own simple T-stat & zones, The t-stats basically become high limits. We set them to 68* or so. The Living room on the main floor gets solar gain so the stats cut out early in the morning and back in late aft. The lower level stats rarely cut out now that I have the reset dialed in. I hired Mark Eatherton to check it all out and to Service, tune & clean the boiler.



When the aquastat went bad on by boiler, I replaced it with an Aquasmart by Beckett. I have it wired to control both the boiler circulator and also controls the DHW circulator along with utilizing the boiler reset energy saving controls built in to the aquasmart along with post purge on the DHW side

This year I replaced the recycled 26-99 system pump with an Alpha, It works great and usually runs in the 25 watt range vs the 200+ with the old 26-99.



Depending on your control strategy, I would have to dis-agree with Zman’s comment to link the primary & system pump. Its been my experience with my system, that the 361 calls for heat from the buffer, and only fires the boiler when the buffer isn’t able to supply the heat needed. My secondary pump runs almost constantly because of the reset curve, the boiler only runs every so often, maybe less than once an hour depending on how cold it is outside. In my situation, if the pump was tied together it would be pumping heat from the buffer back into the boiler most of the time.

Future plans to explore a post purge on the Boiler pump to get the residual heat out of the boiler, even though it’s in the heated space & the heat ‘lost’ is to the house.



Happy Planning & Plumbing,



Tim

PeterNH

No more worries, about the 50g BB being oversized!

Hello Tim,

Thanks for taking time to explain your system.  It is very helpful.

I have a few comments and then some questions.

Wish i had ME nearby to check out my stuff.  But if i understand correctly, he has no part with oil boilers.  :-)

I agree fully with your observation about reverse heating the boiler.

That is not in my plan.

One thing i'm going to reconsider is doing the injection after the bufffer.

Orignially i was trying to keep it simple and just set the buffer temperature to the ODR and let the thermostats handle the rest.

Both you and Scott and a gentleman on a different forum have recommended post buffer ODR. 

I don't have any solar at this point, but i want to provide for it, if it becomes a reality.



The reason for the zone valve bypass around the ESBE, is for post purge.

(and to help bleed air at the initial fill)

I can forsee times when the water temp at the bottom of the buffer will be cold enough to close the ESBE, but there may be heat in the boiler that could be purged out. I plan to use a solar type differential controller to: open the zone valve and turn on the boiler pump (or simply just gravity flow,) when the supply temp at the boiler is higher than the buffer return and there is no call for boiler heat or hot water.

I also want to do a similar purge to the IHW in the warm weather.



Questions:

What type of air elimination devices do you have and where are they located?

Where did you connect the expansion tank?

What size/brand expansion tank do you have?

Did you use IFC's or independent flow checks?





More Later,

Peter











 

Tim Potter

Your 50 gal is going to be great !

Pete, I think your setup is going to do everything you want it to do, especially being you will be there to do hands on "tweeking" to get it dialed in, and if you use the 361, its a learning control.



1) I'm sure ME doesn't hate oil, just in CO there is lots of gas available :-)

2) Yes, Yes, Yes on injection after the boiler, it allows the Buffer to store more BTU's thereby keeping the on & off times longer.

3)In my mind, the Post purge (on a set timer) will be fine till the boiler goes below 113* without the bypass on the ESBE. the rest will keep the boiler warm for the next restart. Remember, with the buffer, you will be having a lower amount of cycles per hour. you can drive yourself crazy with extracting the last possible single BTU out of a system.

4) I didn't have any problem purging air from the Boiler side of the system, its a straight shot from boiler to pump to buffer. The ESBE is on the return side, drawing water from the bottom of the buffer, no air down there. any air in the boiler is naturally going to go into the buffer & then be removed by the Buffer air vent.

5) When I changed the Boiler control to the Beckett, I had a choice of post purge on the DHW side or the Heating side, I chose DHW because that's a Year Round call, & my Boiler is in the heated space, so no btus "lost" so to speak.

6) Spirovent on Boiler loop with a amtrol 15 exp (existing on original system, just kept it, but I probably could have removed it & allowed the buffer to be the air removal).

Spirovent factory setup on buffer. Taco air scoop with spirovent & Amtrol 60, on the secondary side. No air in my system.....

7) both pumps on boiler side are IFC's, injection pump no IFC, Secondary Pump Alpha, cant remember, but I thing no IFC needed on that side.



Attached I have included a couple of diagrams that show how my system is designed. I don't have a good drawing program to illustrate my exact system. Maybe I can wrestle my daughters laptop away from her & use her copy of solidworks & diagram it out someday.



Steve, to answer your question, the 361 looks at the speed of the injection pump. It doesn't know or care that there is a buffer of not, it only sees heat. The control computes how much hot water from the heat source it has to add to the warm water in the secondary side to make the water temp. as the buffer cools, the control ramps up the injection pump to keep the temp where it wants it. on my system, anything over 90% then fires the boiler. The fire continues until the inj pump speed is reduced to under 15%. Hence the long on & off times.

Tim Potter

attachments

Attachments:

PeterNH

May Opyions

Hello Tim,

Thanks for posting the drawings, they are thought provoking.

Any pictures possible?

Where is the Amtrol connected?

Correct,  that the boiler and IHW pumps are on the supply out of the boiler?

 

In Siggy's newest book, all the buffer tanks are shown with the expansion tank and water feed connected to either side of the bottom buffer tank connections.



I'm still thinking about the injection pump.

The zones in my house are wildly different.

At this point everything is baseboard, no radiant.

The second and third floors of my house are pretty close to being super insulated, are not drafty and hold thier heat quite well. Constant ciruclation would be nearly impossible and IMO not needed.. As it is now, those floors heat, no problem, by gravity** alone. Their  zone valves have their end switches diconnected.

The front hall, rarely comes on and there is no need for even temperatures, there.

The porch and garage zones also do not need any sort of even temperatures.

the T'stats are set to 45 degrees. The end switches on those zones are also disconnected. They gravity flow almost constantly when it gets really cold and i don't have to worry about freeze ups, in between heat calls.

The model train room also approaches super-insulation. The end switch is also diconnected for that zone and it heats by gravity no problem.

 

**Of course all the so called gravity zones get a full pumping boost when the 1st floor or front hall calls for heat. Otherwise, presently not connectig all those end switches certainly helps prevent short cycling, to some extent and also helps extend run times.

 



The first floor is more than half, maybe 3/4's, of the heat load. It is also the least comfortable zone in the  house. This zone is where i would base the ODR and IDR temps on. It does have tremendous solar gain, if the sun is out. The model room might need more heat -  with 1st floor indoor reset and a sunny day on the first floor. There is no solar gain up in the train room.

So i think i'm going to stick with my original plan and set the buffer temp to ODR via a Tekmar control based on the needs of the first floor.  I'll try the Auto Diferential on the Tekmar. 

With cooler water temps than i have now, i'll have to see what happens to the "no end switch" zones with the Alpha pump. I think it will be good, with the exception of the model room on a sunny day. Of course a more expensive 401 or 422 series control would take care of the model room, even when there in no need for heat on the first floor.







Peter

PeterNH

Newest Drawing

Here is the lastest version of the plan:



http://home.comcast.net/~k16862/Heat/BB03.JPG



Peter

STEVEusaPA

Tim..

Thanks for posting the piping & wiring diagrams.  Very thoughtful, and helpful.

One quick question for Tim.  In your system, say during a call for heat, the boiler is off, the buffer is supplying the heat, temp in the tank is dropping, and now the sensor tells the boiler to fire.  10 seconds later, the call from the zone ends, does the boiler then turn off (short cycle)?  If not, what makes the boiler continue to run, and to what temperature will it run up to?  I assume its target temp is on the reset curve, but when the zone stops calling (as in my system with the Tekmar 374), doesnt the boiler demand end and the burner shut off?

Zman

Progress

Peter you are making progress. I thought about Tim's suggestion on the boiler pump and think he is correct, With a well insulated, generously sized buffer, the extra storage in the boiler is probably not worth tapping as it will probably cool the system more that it will help.with all your smaller zones, you may have long periods of time between boiler cycles, why not keep the heat in it's nice insulated home. Thank you Tim.

Your design is getting more complex. Is the pump between the tank and the baseboards a VS injection pump?

I am not sure how well the solar will work at it's present location. Solar panels favor lower temps. I am not sure how useful those temps will be in that part of the system.Also, most of you solar output is in the summer. How will you utilize it? Unless you intend to put up tons of collectors that also heat your DHW, I think you would be better off doing DHW only on the solar.

Carl 

PeterNH

complexities

Hello Carl,

"Your design is getting more complex. Is the pump between the tank and the baseboards a VS injection pump? "

Yes.

 

Bit more complex, yes.

 

Agree about the solar and DHW for the most part.

The garage and porch and the hobby room, when unoccupied, and probably the 2nd and 3rd floor don't need very much in terms of temperatures to keep warm.

It would seem that if there is any extra solar heat available after domestic needs, that it be great to put it to good use.

We only use about 25-35 gallons a day of domestic hot water.

Perhaps i should make the drawing even more complex, and find a way to add any solar energy just to the cooler zones, not the whole system.

 

Or just do DHW, only,  and be happy.



Peter

 

Tim Potter

3 Concepts

On my system, I made 3 separate concept changes to the original (disaster) design.

1 was to add a buffer tank to limit short cycling, next was to adapt ODR & Constant circulation to increase comfort, & then I changed my secondary pump to the Alpha and removed the dP that I added to stabilize the flows using the honker 26-99 pump

In order to get "your mind’s eye" on this, it would help to read Tekmars essay's http://tekmarcontrols.com/resources/essays.html

There is a lot of reading there, and it’s all there to support their advanced controls, but it’s very informative.

Constant circulation is your friend, remember, when your reset curve is dialed in correctly, you may only be circulating 120* water through the loops instead of 180*. That temperature is calculated by the control to only deliver the exact amount of heat that is needed to maintain your set room temp, say 70* no more, no less is the goal.

Mark Eatherton relates bang bang (bang, its on bang its off) vs constant circulation the same way as driving your car. Constant circulation is like driving on I-70 with the cruise control set at 70. You’re at a steady speed, no violent jerking around, up hills, down hills your are at a steady speed. Bang Bang is like driving with a switch instead of an accelerator pedal– ON, you accelerate at full throttle until you reach 140 mph, then OFF, you coast back to zero. Then switch ON, back to 140 mph, etc. you get it. Your average speed is still 70 mph, but it’s not a smooth ride.

Now say you have adopted constant circulation, without a buffer tank in the system, the low amount of heat needed to Inject to the zone to maintain say 120* in the loop would drive the boiler crazy with stop start cycles. You see how they both complement each other.



Now for those zones you want to maintain below 70* the t-stat in that area becomes the high limit for that zone. Set it where ever you want it. In my system, the Garage is set to 50*. By allowing the cooler 120* water to circulate in that zone, the on time is longer, but at a lower temp, *(same amount of btus in an hour, just spread out over a longer time) results in smoother heating, until the t-stat cuts out and drops that zone.

Now because you are having zones coming on & off at random, it drives your secondary pump crazy, so that is an excellent application for an Alpha or Wilo or the new BumbleBee when it comes out to maintain proper flow no matter however many zones that are open, no need for partial gravity feeds etc. they adapt themselves to changing flow.



I see the new drawing is listing a radiant system also. You could look at the 374 control; it can control 2 different temp systems, 1 for the baseboard and the other for the lower temp radiant, still using constant circulation for both using 2 alphas. It appears to be about 2x the price of the single zone 361 – go figure…



As far as pictures, I looked, and I don’t have any on the system as it stands now, but the good news for me is we are headed out to the Mountain House next Fri for a week of skiing, so I’ll take some then.

I’ll re-post up one of the drawings I have marked up some of the expansion tanks are attached. My Boiler had the water feed coming in to the top of the boiler, and the existing design had a spirovent & amtrol 15 expansion tank on the output line of the boiler, it’s the PONPC for that design. When I added the 80gal BB, I added an amtrol 60 to the air scoop on the secondary piping. It seems to work well, but I can see where adding the water & exp tank to the buffer would be good also.

You are correct, the 007 boiler pump & 007 DHW pump are both on the Boiler output line.

The constant circulation & using t-stats to limit the temps will really smooth out your first floor temp swings, you just need to embrace the technology, its tried & true. If you used a 361 for a control, you could put your indoor sensor in that space to base the temps on your most used area.

I contemplated making my buffer operate at the system temp, because I didn’t believe the electronics could possibly work, so I wanted the buffer to be an 80gal source of system temp. BUT… I was talked in to making the Buffer part of the boiler side, BOY am I glad I did it that way. The Tekmar controls secondary temps to within 1* of its requested temp, and the buffer operating at Boiler temp makes the on & off times very long (efficient)

In your case using an Alpha & ODR, I would consider hooking up all the end switches so if a zone calls, it gets heat.



Steve, The way my control works is there has to be a call for heat (end-switch close) and a need for heat (injection is running close to max) for the boiler to fire. You are right, if there is a heat call and the Inj pump is turning 90% or more the boiler will fire ( sometimes fire, it’s got some crazy logic built in), but if the heat call goes away, (end-switch opens) the boiler shuts down, so there could be a time that that happens, but not likely to happen often. I do see it on DHW calls occasionally, but the post purge gets the heat out of the boiler. The buffer in my system operates at boiler temps, set by the high limit on the boiler aquastat. The only time we don’t get to high limit, is when the boiler is recharging the buffer, and the injection pump ramps down, the control (there is extensive logic built in to those) senses that no more heat is needed, so it shuts off the boiler before high limit. The 374 appears to be on the same logic as the 361. I can see your concern with that, but with the addition of the buffer, your cycles will go way down along with the chances of that happening.



Wow long post



Tim

Tim Potter

Attachment

Still having attachment issues....

STEVEusaPA

Thanks again Tim...

For taking your time to get somthing thru my skull .    Great explanation, very detailed.  Hope I'm not hijacking Peter's thread.

STEVEusaPA

oops...double post

Zman

I Like it

Peter,

I like what you have going. Most of the details everyone is talking about now boil down to personal preference.

I have been thinking lately about boiler protection during DHW production. My mod/con spends a great deal of time in condensing mode while making DHW. A good this for me, but a bad thing for conventional boilers. I think the improvements in indirect tanks has made this a reality in recent years. I think I would consider moving the indict to the other side of the boiler protection loop.

Carl

PeterNH

Fully convinced

Long post. -  The review of the whle topic is very much appreciatted.

Thanks Tim !!!

 .

I have read the Tekmar essay's, most of the Caleffi idronics and have read Siggy's newest Hydronic Heating book a couple of times, more or less.

The new first floor radiant won't give much heat.  10 btu's a sq. foot will be a huge sucess. There are a lot of layers of old floors and post and beam framing. In any case, imo, it will be worth the effort.

 

OK, that's it, i'm fully convinced.  I'll do the injection pump. I did include it in the latest design yeaterday. All the end switches will be connected.

No worries Tim.



 

As far as controls go.

I'd really like to use the newest modualr tN4 stuff in the 42x series..

It is expandable without waste and more than one room can provide indoor feedback.

Expensive for sure.

(However the only drawback seems to be that the 42x controls can't do what the 363 can do. In the event that i ever have any excess solar energy to use.)

 

As long as i have the basic plumbing correct, which is my bigggest concern. 

I'm not worried about the control system.  There are more than a few options that i'm sure will work. The electronics are easy for me.



Peter

PeterNH

Steve

Great questions. 

I have been wondering the same, about the potential short cycle and more.

IMO, the buffer wants to be maintained at the computed ODR temp. Plus a differential.  Or a little higher.

The injection pump should remove the effect of the differential from the supply and provide a supply temperature based on the indoor feeback of a given group of zones.  That there is any Tekmar control that can exactly do this, remains to be discovered.  On thing that rings in my head from reading Siggy's book, is the comment he made re: buufers and the need for more advanced control methods for buffer tank systems. Something we haven't really seen just yet.



Please stay involved.

And, any more advise on the piping design is greatly appreciated.



Thanks,

Peter

Tim Potter

Keep up informed

Let us know of the final design, & how the progress is coming. Mud season is upon us soon. Pictures of progress is always appreciated



Tim

Tim Potter

what drawing program

OBTW, what drawing program do you use, I apparently need to "up my game" in that aspect



Thank You:



Tim

PeterNH

Thanks for the encouragement Z

 

I have been wondering/worrying aboout the same thing Carl.

But i'm not sure how to make the plumbing work.

My old super stor has probably got a foot of iron sediment in the bottom.

It typically takes 3 1/2 minutes to get the return temp above 115 degrees.

Right now there is protection by the low limit on the aquastat. The pump shuts off if the boiler temp goes below 115 +/- .Turns on at 140.

 

And after that the return heats up rapidly.  The differential is usually only 10 degrees and less as it heats up, it goes down toaround  6.

It fires once or twice a day, unless it's laundry time.

 



Peter

PeterNH

Tim

That is John Siegenthler's HydroniCAD.

It has a few major "gotchas"  (grrr.)

But i would reccomend it any way. 

In the hopes that more users might mean possible improvements.



Peter

Zman

There is way

I think P1 an P 2 need to move outside the boiler loop. I better check the books before I say something stupid

PeterNH

Rocket Science ?

or - Not that critical????

If i move P1 and P2 to the supply, it would work.

However.

Then i would not be "pumping away" in the JSiggy recommended method for use with buffer tanks.

Move the PNOP to the Spriovent on the supply, but then the System supply pumps are not exactly pumping away. MAybe it wuold be ok?

Or.

Maybe the IHW needs it own ESBE?



Dunno'

Peter