advice on boiler brand/sizing

jimmythegreek

Long story short I have a 3 family each unit is its own floor, 3 boilers 3 water heaters each unit has one of each.  2 boilers are on last leg and 2 water heaters.  2 boilers are 90k btu and the basement unit is 75k.  They can handle the size of units, its HWbaseboard in each.  On super cold days here in NJ they may run almost continuosly, the units are oceanside and poor insulation but good windows.  Anyway Im gonna yank them all and go w a single boiler and a domestic storage tank.  Im thinking 300k btu range, I need 275 for max load from measuring, is 25k extra enough for a storage tank?  Anyone can recommend a good model that has a paired tank system?  Also w 3 heating zones and a domestic loop I will have 4 zones total, the domestic loop and basement unit has no head lift to deal with for circulator pumps, but the 1st floor has 8 feet of lift and the 2nd floor has 17 feet of lift needed, I had to upgrade 2 years ago to a grundfos 3stage pump to get good circulation to the top floor, the rest taco 007s.  Im thinking a zone valve and circulator for each zone, I know they make fancy boxes that do the switching relays and all that, Im all for it if its worth the  $$ and cuts my install time down.  Any advice and models to look out for are appreciated.......thanks in advance

lchmb

have you

done an actual heat loss for the building? What are you interested in? Condensing- non-condensing? And reference zone valve and circ for each floor that isnt necessary. You can use zone valves for all 3 zones and use the grundfos pump to supply what you need (check the alpha). As far as a zone control box, highly recommend it...makes life so much easier...

CMadatMe

Heat Loss

Agree with Ich, start with a heat loss. Existing radiation only gives you your capable output not what you need. I take it your going to need to line the chimmney so a Burnham ES2 would be a great choice. It's 85% efficient and offers a simple plug in card if you want to add outdoor reset which will save your more money in your fuel bill.



How many people in these apartments? Asking for the DHW load.

jimmythegreek

did a heat loss calc

I did a heat loss calculation, i need 110k btu for each of top 2 floors and 70k for the basement.  The basement apartment is 5 feet underground and 3 above so thats why its so low.  The net btu of the 3 boilers there now is 240ish so they are undersized.  I dont want to reline chimney, If I have to go condensing boiler i can do direct vent the utility room has 2 outside walls with clearance for exhaust and intake.  I see alot of 300k btu boilers are well past 5 grand, WM are like 6 and change, I am trying to stay under 5k and have a decent boiler.  I also dont think I can use just 1 circulator, when i replaced the top floor w a 3 stage grundfos the heat worked really well, the gas company replaced a month earlier (2 yrs ago) the existing circ w a taco 007 and it couldnt pump water fast enough for the loop and 17 ft of lift.  I think 1 circ for each loop or a highflow single pump, a regular job wont do it.  I will do the control panel for ease of install w 4 zones, 3 heat loops and 1 DHW loop.  Is there any need for balancing valves or the loops will just call and satisfy their needs as it goes?  any recommendations u can give me on boiler, storage tank, and the control panel?  I did some research and taco and afgo both seem to have a nice one. 

and they are 2 bedroom apts. currently just single people in each unit, max of six, so it could possibly have a decent domestic demand, but currently there are three 40gallon direct tanks, one for each unit

thanks alot

CMadatMe

Scratch, Scratching

My head. I think you need another opinion on the heat loss. A loss that high for a 2 bedroom apartment doesn't look right. Those apartments would have to be in the neighborhood of 3,000 sqft, uninsulated and old windows. Same goes for the basement sounds awful high.



We don't count lift when sizing a circulator pump. It doesn't pump water rather it creates a differential in the system. To size head we take the distance of the longest run from the outlet of the circulator thru the zone and back to the inlet side, multiply by 1.5. We then multiply that times .04 to get head.



We then calculate are gpm requirement based off our heat loss.



Example: Longest run 100' x 1.5 = 150 x .04 = 6' head



Heat loss is 100,000 btus . System runs on a standard 20 degree differential ( delta-t)



gpm = btuh divided by (delta-t x 500)

10gpm = 100,000 divided by 10,000



I need a pump that can move 10gpm @ 6' of head.



I would suggest you get a second opinion on your heat loss.

jimmythegreek

i thought so too

Little more info.  The building is concrete block exterior w a parge coat, kinda old school stucco look.  Its 3rd house from ocean, very cold winds there as well in winter.  There is NO insulation in the outside walls at all, zero.  They have 3/4 furring strips nailed to concrete block and drywall nailed to that.  Thats it. Windows are new there are alot of windows and the whole front 1/3 is open room layout, kitchen,family,dining room, big windows.  Windows are new but replacement windows, kinda crappy install, maybe standard at best.  Each unit is roughly 1800 sq ft., and there is definitely not enough baseboard for the units.  They couple years ive owned it I spend very little time down there.  I have stayed there a few times in winter and had Tstat at 50.  If I set it to 70 it would take 36 hours to raise to that temp, I would say 1 degree per hour, thats with a 96k WeilMclain HWBB setup, same as all the rest, diff boilers in each.  the other is a old american standard, another a sears job, both those from early 70s.  The WM is 8 yrs old the other 2 I beleive original.  Either way when I changed the 007 to a grundfos 3 stage set on high the heating improved dramatically, took about 15 hrs last year in dead winter to go to 70 from 50 degrees on a 20 deg day.   I found decent pricing on a WM PFG 5 or 6 series, and also crown and utica boilers.  I have WM in my home and another building, I like their products.  I was also thinking of WM for the DHW, opinions?  Is there any other way to get better heat out of the existing baseboard without adding length to it, I was thinking maybe high output?  Is it a myth that faster water circulation will improve heating recovery speeds?  Seems me changing the pump on the top floor unit worked wonders, then again I did purge it very well afterwards, was kinda airbound previously.....thanks

CMadatMe

Baseboard

No moving the water faster does not make it heat up quicker it actually does the opposite. If I move it faster I cannot transfer the btus from the water to the board. Your just sending hot for a ride around the system.



Sizing the boiler bigger also does you not good. I can have a boiler that is a millions btus but you can only deliver what the heat emiiter can put out. Going hi cap would be a better way of tackling your lack of baseboard capability. You will get approx 260 btu's a ft more out of the hicap over the standard board.