150k btu Retrofit - Pump sizing, Heat load software, Control strategy

NYplumber

<span style="font-size:16pt"><span style="color:#ff0000"><strong><span style="text-decoration:underline;">EDIT: Pictures below.</span></strong></span></span>





Hi there fellow HeatingHelp members.

Long time reader, loads of info and interesting posts daily, yet first time poster.



I have been in the service end of the business for quiet some time, installed a few retrofit boilers, but for the most part learned what not to do in the boiler room as to make everything easyer to service later down the line.

Here is the first of this larger caliber retrofit in an early 1900s house.

Current heat load using Taco software: ~150k btuh. Five zones, two monflow (55k btu & 30k btu) on the original house, and three (zone valved loops) on the addition (totaling 62,500btu).

Current system: 200k input Peerless on monoflow loops (cast rads), 80k input Slant-fin on three (fin tube) zones from the addition.

1 1/4" monoflow on 55k btu

1" monoflow on 30k btu

1" feed to the crawl space of the three zones adding to 62,500 btu



New system will compile of two cast iron boilers (perhaps a Peerless boiler) feeding a Boiler Buddy 30 gallon buffer tank using a Tekmar 261 staging control with the sensor in the tank sensor well using a low of 150*f and a top of 190*f. The zone side will compile of pumping away (DUH!) with three pumps, zoning the monoflows with pumps and the addition with three zone valves on the return side (due to a 1" copper feed to the deep end of a crawl space).

Controlling the zones is as follows: The monoflow pumps will be controlled using a Taco SR502, and the three zone valves with Taco ZVC403.



To the questions...

Which pumps?

On a 10*f delta-t 55k btu monoflow loop specs a 11gpm pump with 12ft head (200ft piping). 30k btu monoflow loop specs a 6gpm pump with 12ft head. For the 62,500 btu zone valve loops specs 12.5 with a 12ft head.

Im as confused as can be as to what circulators would properly belong on the monoflows. I looked at the 00r, 0012, up26-120, up26-64, up26-96. All these pumps seem expensive from the 007 that usually specs into the small jobs I do.

For the three zone valve loops, I plan on a Grundfos Alpha constant head pump. The question is whether to keep constant power to the pump, or let the Taco relay box turn it on and off.



<strong><em>Tips for the correct pump sizing would be greatly appreciated.</em></strong> Lets try to use cheaper pumps. ;)



On another note, I am looking for another heat loss toll instead of the Taco load tool. Input here will also be helpful. I contemplated Writesoft, but would like more choices.



Thanks,

NYplumber



Edit: If I may add, does a sx30v expansion tank sound like the correct for a system of this water capacity?

NYplumber

Grunfos

How does the Grundfos UPS43-44 pump fit into the monoflow loops?

NRT_Rob

well

I think a 10 degree dt is overkill. if you design for a 20 or even a 30 you can cut your flow in half or by 2/3rds. that should help quite a bit, though your supply temp might need to be 5 or 10 degrees hotter.

NYplumber

UPS 15-58FC

Rob, how does a Grundfos UPS 15-58FC sound when using a 20* delta-t?



50k btu monoflow loop: 5gpm @ 12ft head

30k btu monoflow loop: 3gpm @ 12ft head



The curve shows that speeds one & two can be used with success.



Is this the correct formula? BTU / Delta-T (500)





These smaller 15-58 pumps are more cost effective.





On a side note, how would one calculate the needed temperature increase for the slower flow rate?

Thanks in advance.

NRT_Rob

sounds good.

looking just at the flow/head you're good there.



Your average temperature requirement is supply temp minus half dt. so if you know you needed, say, 140 Supply (SWT) at a 10 dt your average temp was 135 deg F.



If you have a 20 degree dt, half of that is 10, and so you would need a 145 SWT to get the same 135 average water temp.



in other words, half of the dt increase must be added to your supply temp requirement.



and your formula is correct for straight water. Hope that helps!

NYplumber

Boiler install completed

One photo, many to come.

All insulated for efficiency, not to hide the solder joints.

Two cast iron standing pilot boilers, BB 30, Tekmar boiler and odr controll, Grundfos pumps (Taco on the boiler), five zones total.



Please comment, criticize, discuss.

Henry

Standing pilots/efficiency??

It looks nice but why go with standing pilots if the client wants energy efficiency? In Canada, standing pilot boilers are no longer permitted a they do not meet the minimal energy efficiency standard! Maybe not so in the US?



Regards,

Henry

NYplumber

Simplicity

Its more about the install and proper sizing rather than the boiler being mod-con.



The customer asked for simplicity. If the system was broken, a savy homeowner can diagnose the issue. Also, coldest night of the year when a spark control seizes to work theres no way to know the truck will have a replacement.

NRT_Rob

not exactly

mod/cons will blow any non-mod con, properly sized or not, out of the water for efficiency. High temp or low temp.



the "mod" is very important.



the "con" applies to nearly any system for half the winter or more.



simplicity is good, not saying you made the wrong choice, but a lot of efficiency was left on the table here.

CMadatMe

A Step Further

Would have also zoned it with Zone Valves and just used that Alpha pump as my system pump. I believe reading a few posts above your only trying to deliver 8gpm at 12' head. Why the need for the 150K if you only needed to deliver 8gpm? Nice quality work on the install.

NYplumber

Return on the investment

Return on the investment would have not payed off with the cost of a TT Solo due to the location of the boiler in the middle of the basement. Running long intake & exhaust vent in cpvc wouldn't have been practical with the already low ceilings (pitch needed and low ceilings don't go well together). The boiler could have been relocated to an outside wall, but the cost for the gas line and piping along with the price of a mod-con would have been enormous in comparison to the current setup.

NYplumber

5 zones. Two monoflow, three on zonevalves.

Thank you HVHEHCCA for the compliment.



There are five zones, totalling around 150k btuh. 55k, 30k, 62k.

At a 20*delta-t that's ~14 gpm.





I was wary to zone the whole residence using the autoadapt feature on a customers home. It turned out to work nicely on the three small zones.





Feel free to view my pictures HERE .

NRT_Rob

doubtful

unless you have demo costs or something involved with the gas line running. mod/con vs cast iron and you can expect 20% fuel differential or so. on a 150k load in NYC, that's real money.



and as far as the alpha is concerned, we don't use the autoadapt feature at all. but the constant pressure settings are excellent. 14 GPM at 6 feet of head, constant pressure 1, isn't bad... though I probably would have used 2 in this case with such a high flow, separate system pumps. Still would have used less than a single 15-58 on high speed.

NYplumber

Bypass?

Would the other six settings other than the auto adapt require a bypass valve when only part of the zones are calling? I'm unfamiliar with the details on the ecm pump.

NRT_Rob

no

not the constant pressure modes.



the fixed speed modes, might, maybe.

NYplumber

Results

Results for the past heating month on the customers bill was a reduction of 37% cubic ft of gas from 481cubic-ft to 306cubic-ft.

The month was colder too, so the savings is more denoting.



The past months had significant savings too, larger than the past month.

tim smith

Re: Modcon etc

You did a pretty nice job, although I too would have put modcon(s) in and just ran my flue pipes up the chimney. Do it all the time. If largish tall house, we use stainless flue pipe as this brings the weight way down and we use cables with stainless draw bands dropped down and couple mid points to take care of the vertical pull. We then build strut brackets at top and bottom of chimney for the rest of the support and stability. I bet another 20+ % savings could have been found. Still, I think you did a admirable job. Tim

NYplumber

More pictures

AFred

Bravo

Awesome job!



I think it was a good choice on those crowns, talk about minimal repair parts!

I cant put in equipment with piolts anymore, sad.

-Andy

NYplumber

TAKE A SEAT! Results

Results are in. For the same period this year in 09, the current bill was 53% savings in ccf/nat-gas.

The backup generator ran for two days this month.

Gordan

Heating degree-day difference?

Did you take it into account? It seems like we've had milder weather in the Northeast this year than last, so far.



Nevertheless, at least some of those savings must be from the heating system improvements, so congrats!

Jean-David Beyer

seems like we've had milder weather in the Northeast this year than last

Seems like that to me, too.



According to my gas bill (New Jersey Natural Gas), last December I used about 95 Therms. This December, I used 60 Therms.

Gordan

Though, it occurs to me that the comparison he had was with 2009

I still think that this year has been milder, what do your bills say about that, JDB? :-)



 Edit: looks like 12/2010 was about 10% more heating degree days than 12/2009 for both NY and NJ, so I'd expect your 12/2009 utilization to be in the neighborhood of 86 therms. Close?



Applying that to the posted savings, it would then seem that 30 percentage points would be attributable to milder weather, which still leaves 20% and change, which ain't nothin' to sneeze at! I based this on state-wide HDD data and your bills, though - I couldn't find 12/2011 HDD data - so it's a very crude approximation.



Another edit: though, if the period in question includes November, 2011 was about as many HDD as 2009 (96%). Unless the utility includes the HDD info for the billing period, it'll be difficult to parse out how much of the savings can be attributed to what.

Jean-David Beyer

what do your bills say about that, JDB? :-)

For December 2009, it was 60.41 Therms. Since then I have made some changes to the reset curves, but they may not have made as much difference as the change in the weather. That was the first December I had this system.



For November 2009, 27.09 Therms. For November 2010, 38.55 Therms. For November 2011, about 35 Therms (cannot find the bill, but the graph shows about this).

Gordan

Wow, 86 was way off

So either the NCDC HDD data was not representative of your area or your usage does not track heating degree days, or whatever changes you made to your reset curve made things much worse efficiency-wise (very unlikely), because your usage in 2009 should have been a lot closer to 2010 than to 2011. Unless, of course, your December bill is for November usage, in which case HDD data would predict it.

NYplumber

h d d

I used 09, since the '10 bill was an estimated reading.

I did not find local data for anything before the '11 year from the weather stations locally, however I may not know which websites to collect the data. Data for this month wasn't available either. Point me to a hdd source and i will do more accurate calculations.

Jean-David Beyer

Unless, of course, your December bill is for November usage,

My bills straddle the months. They go roughly from the 15th to the 15th. So my "December" bill is from about Nov 15 to Dec 15. 

SWEI

data sources

Check out http://www.weatherdatadepot.com/ and http://www.cpc.ncep.noaa.gov/

NYplumber

H D D

Thanks, that first link works well.



After adjusting for a more mild Decmber this year, savings is 34.5%, still a "hold on to your hat" savings. (Actual CCF savings, monetary savings will be more due to increase in NG cost.)