Advice new boilers for two apartment home.

Dana.

I have installed both.

When you add the stainless steel vent pipe, which adds nothing to efficiency, I pay roughly $3000 with "optional" outdoor reset.
There really is no justification for a direct vent cast iron boiler any longer. They are for old women who naturally don't have the sand to try something different.

The EC is very good for a cast iron boiler and serves well where the chimney is good, fuel cheap and the budget tight.

The HTP-UFT 80 runs about $1000 less.

Bring it, baby!

I'm and "older guy" and you couldn't force me to put 100mbuth anything in this house, even before I did the Manual 'J'.

If you follow Dana's advice on improving the envelope, hardly ever wrong and let me do the mechanical specs. you will be a world ahead .

 

Morgan- don't get me wrong- I'm a fan of the UFT-80 (which is why I keep bringing it up.) The 10:1 turn down ratio makes it suitable for something like 95% of all houses in the US, and clearly more than enough boiler for this one. A Lochinvar CDN040 might work pretty well too, but it might be marginal for the "before building upgrades" picture at about half the high-fire output of the UTF-080, and a slightly higher minimum fire.

But I wouldn't want to just let some hack proposing replacing a pair of 100K cast iron scrap yard specials with an other pair of 100K cast iron boilers install a UFT-80. Said hacks probably could install a 3-plate Burnham without screwing it up (all the while muttering under their breath that it's way too small.) Not so sure how they'd fare with even a simpler-to-install-than-some mod con.

This isn't too different from the situation John Molyneux encountered when looking to right-size a new boiler on his Maine place last year. All the local contractors were throwing 100K+ boiler proposals at his ~25-30K design load. He had to dig pretty hard to find a contractor willing to right-size the boiler, but the results were (apparently) worth it in the end.

 

I am glad I don't live in those places...

I have to remember; the worst boiler is better than any scorched air furnace...then I take a deep breath.

You're still my math hero.

 

Thanx!

 

Ok, little confused with the math. I just select one billing period, and add up the HDD for each day within the billing period, counting only the first or last read (not both) of the billing cycle?

For therms, am I converting the therms used in one day or one month to BTU's?

And then am I multiplying the BTU's by the DOE output of the boiler, you mentioned dividing DOE out by BTU in?

I'm using the boiler in my unit for this calculation, since I don't have any accurate bills for the first floor unit. My boiler is a Peerless MI-04, 105K in, 85K out, and 75K DOE out. Adding up degree days for Nov 2015 billing cycle, starting with the first day and not including the last, I came up with 629 HDD (that sound right?) Therms was 130.28 for this billing cycle. One chart I see is showing 0 deg. and the other -5 deg. for design temp in Chicago.

I forgot to mention, the 20K btu space heater keeping the first floor warm is also on my meter, so that may skew the calculations.

Your right, I had the ratings for 1st floor wrong, 100K in, 76K out, 68K DOE.

The guy who didn't like direct vent suggested running new two new B-vents, if it were one and not too big could prob work out a space but there really isn't a good clear chase to run it that doesn't interfere with the bathroom I want to put in the attic. I don't want any more chimneys cutting through the attic in a space I want to finish nor to loose the linen closets on each floor to run them.

 

Here's a straw man calculation for illustration purposes. Say your meter reading was on 11 December, then again on 13 January. Add up the HDD from either 11-December through 12 January, or 12 December through 13 January, but NOT 11 December through 13 January. This is because the meter readings only captured part of the day on the meter reading date. If you have two wintertime bills, use the whole period, throwing out either the HDD for either the first or last meter reading date.

Say you added up those base-65F HDD and it came to 963 HDD, and during that period you used 287 therms (=28,700,000 BTU)

Assume the boiler's nameplate says 100,000 BTU-in, with a DOE output of 76,000 BTU (/hour), like yours, a 76% steady state efficiency.

So the source fuel BTU that went into boiler's burner was 28,700,000 BTU, but only 76K/100K of that went into the house (the rest went up the flue), so the house only used 0.76 x 28,700,000 BTU= 21,812,000 BTU, over 963 HDD.

The amount per heating degree day is then 21,812,000 BTU/ 963 HDD= 22,650 BTU per heating degree-day

Since most days have 24 hours, that would be 22,650 BTU /24= 944 BTU per heating degree-hour.

Let's assume your 99% outside design temp in your ZIP code is +1F. You used base 65F as the heating/cooling balance point presumption, so to be consistent with the model, your heating degrees are 65F - 1F = 64F heating degrees.

That implies the heat load at +1F is: 64F heating degrees x 944 BTU per heating degree-hour = 60,416 BTU/hr.

That's probably a bigger number than what yours will turn out to be, but that's the basic methodology.

In a brand new code-min or very tightened-up and well insulated older building it's usually better to use base 60F for this calculation, but the difference in the derived number isn't usually very much. At your level of oversizing and the age of the boiler means it's efficiency is much lower, and the amount of heat that actually went into the house is less, thus the true heat load is actually less than the derived number.

For most of the Chicago metro area 0F is close enough to the 99% bin that you might as well use 0F as the design temp for running the calculations.

The efficiency of the wall furnace is probably 78-80%, not higher than 82%, but it's not actually keeping up with the load once it's in the teens, so the indoor temps might skew a bit lower, but if you just assumed all of it was 75% it would still be a firm upper bound.

Another way to rough it in for the zone with the space heater: If that heater is 20K-in and 16K-out and it's mostly keeping up until it's colder than +15F outside, that's 50 heating degrees (base-65F), and 16,000BTU/hr so the load for that zone at +15F is 16K implying a load that grows by 16,000/50F = 320 BTU for every degree below 65F. So the load for that apartment at 0F (= 65F heating degrees) would be about 320 x 65= 20,800 BTU/hr.

For an 800' apartment that would be a load to floor area ratio of 26 BTU/hr per square foot, which is a bit high for an uninsulated space with an uninsulated basement below unless it's leaking a lot of air. I probably is leaking a lot of air due to the combination of the leaky foundation and balloon framing.

BTW: If you spray closed cell foam the foundation there are a few less-damaging options than just any generic 2lb foam. Lapolla has in the past year released an HFO1234_ _ blown 2lb foam, called Foam-Lok 2000 4G The HFO used has a global warming potential roughly that of CO2, rather than 1000x CO2. Another alternative would be water blown 2lb foam such as Icynene MD-R-200 or MD-R-210 (but not MD-C-200, which is blown with HFC245fa) or any of Aloha Energy's 1.8lb foams. Lapolla and Icynene are likely to have installers in your area, not sure if Aloha does- they're a much smaller player working primarily in the New York/New England region. Both the Aloha and Lapolla Foam-Lok products are in the R6/inch range, the water blown Icynene about R5/inch, but a couple inchs of ANY of those would be a huge improvement over your current foundation & infiltration losses.

A single condensing UFT-80 would be cheaper than a pair of ESC-3s, and according to BadgerBoilerMN (whom I would take at face value on this one), when you factor in the stainless vent required for the ESC-3, the installed cost of the plastic-vented UFT-80 should be comparable or even cheaper. It's worth getting it quoted.

Even a right-sized atmospheric drafted unit with a B-vent chimney would still leave you with a major flue sucking the basement to negative pressure, driving air infiltration, increasing the he heat load. Seriously, direct vented combustion equipment is always going to be better, since it allows you to tighten the place up to even PassiveHouse levels of air tightness with zero risk of backdrafting, and doesn't introduce the parasitic heat load of a flue.

 

The heater on the first floor is one of those vent free ones that they sell at the big box stores that doesn't vent out sits on a floor stand. A friend loaned it to me to use. The first floor is vacant, and the boiler was leaking very badly between two sections. I just shut it off and drained it, and am using the heater to get by for now, just to get some heat in this unit. It is hooked up to my meter.

I've been researching a few sites on the spray foam. One question I do have is will any trapped moisture in the stones or bricks freeze in the winter? Could it freeze and damage or cause the bricks to crumble? Right now most of the efforescence I see is inside, not so much on the bricks outside. Some of the bricks are crumbly now probably will have to be repaired or replaced. There is old paint on the inside, some peeling off. Can the foam be sprayed right over this? I'm thinking I will have to do some repairs and tuckpointing before. The stone is solid except some of the mortar in places is loose and seeping. Would parging the brick be a good idea?

I wasn't going to do the B vent, don't want another chimney.

Thanks for explaining the HDD calculations, I'm gonna give it another shot. I keep going back and forth on CI or moduating. Only reason I was considering CI mostly was if I was going to do a DIY install, but the smallest ESC's are 60K btus, and if I needed two yes that would be more money. I guess the other reason is familiarity, I'm familiar with CI boilers, and the controls seem simple and I know they can last 3 decades. But I like how the modcons can modulate the BTU's to the load, so if one unit is calling and the other is ok the boiler adjusts to that, whereas the CI can't do that. Two boilers would divide the loads between the units but will probably be more money.

I think my biggest concern with modcons is reliability. I've read so many horror stories of them breaking down, ridiculously expensive parts, having to wait to get the parts, and heat exchangers rusting out. I know I've read on here many times it's all about the installer, and I understand online reviews are mostly from those who had bad experiences with them. Not against newer technology just concerned since it's going to be a lot of money and it seems hard trusting anyone.

 

Freeze thaw spalling of the brick is remotely possible in your climate, but not likely. It would be of much higher concern for brick buildings in places that are actually cold, say Winnipeg. The porosity and hardness of the brick is also a factor. If it was going to be a problem it's likely that you already have a few places where it's spalling. Decent roof overhangs (preferably with gutters) to limit splash-back wetting, and paying attention to surface grading/drainage to keep the near-grade soils near the foundation dry is usually more than enough to keep foundation brick from spalling in a US climate zone 5 type climate. (I live in a comparable climate, and have yet to see spalling issues on a foundation that was related to insulating and sealing the interior, though I've seen minor spalling related to chronic splash-back wetting.)

While it's better to clean up any loose crud on the walls first, at 2" the foam itself is fairly structural. as long as the surface of the foundation sill and the top of the foundation is fairly clean it'll be fine.

Talk to a competent mason as to whether a parge would do any good. The original mortar type and the type of brick make a difference. It can go either way. The 1890s house that underwent the deep energy retrofit had a mortar that a sacrificial parge wouldn't even stick to, they just touched up the mortar using a hard portland cement & sand type of mix and sprayed directly on the brick. It shows no signs of spalling despite parts being buried in heavy snow-drift 2 out of the past 3 winters. (Last winter there was 10' of snow in that neighborhood which was a near-record, 9' of which fell in only 6 weeks.)

The controls on an ESC aren't just dumb aquastats- it's features are programmable, and there are optional I/O cards for interfacing to things like an outdoor temperature sensors to be able to auto-adjust the system temperature in response to the outdoor temperature to a response curve that that YOU program (called "outdoor reset", a standard feature with almost all mod-cons. )

There aren't really many direct-vented or power vented cast iron options out there. If you're getting rid of the chimney, a right-sized mod-con is probably going to serve you better in the long run.

Aluminum heat exchangers on mod-cons have a spotty record, and are more sensitive to system chemistry than stainless steel, which is another reason I favor the UFT-80 over some others. It's a fairly new product maybe on the market for only one maybe two years (?) but it's from a company that has a lot of experience (and generally good experience) with modulating boiler technology, and generally good support (at least in my neighborhood.)

Even the best mod-cons can be done-in by a lousy installer with poor local support, which is why polling the local distributors & reps for contractor recommendations is usually a good tactic, far better than picking random "Heating & Plumbing" contractors out of a phone book. Hydronic design is more than just a plumbing exercise, and (as you've discovered), there are a lot of people installing boilers who can't even do the napkin-math on what's appropriate. I would imagine that there is local distributor support from most boiler manufacturers in a market as big as Chicago.

The more you know about your system and load numbers, the better you can vet the contractors, and you'll be in a position to TELL them what you need/want rather than ask them. It could be that 9 out of 10 contractors won't want to listen to what you are specifying and either submit no proposals or propose something else, but you should be able to find somebody who does. John Molyneaux went through this process last year based on advice from this site, ended up with a contractor who installed Bosch mod-cons but his was the first house the contractor had installed the smallest-of-the-line version, and (apparently) was still a bit skeptical on the sizing despite both a Manual-J and fuel-use calculated heat load estimates that converged in a narrow range.

 

I did the calculations using my Dec gas bill, at 861 HDD. I came up with 45,760 btu's for my second floor unit, which seems right but then the small heater on the first floor could be skewing the figure, so I guess it could be a little less than that. I would assume the first floor would probably be about the same, even being above a now unheated basement, and having a heated second floor space above it.

Basement is mostly going to be storage but should I still put one or two radiators down there and figure that in with the load calculations? All of the supplies are copper and there is no heat sorce down there now. When I got the house 15 years ago there was an old Siegler gas heater down there improperly vented out the wall, and I removed it.

Except for the downstairs kitchen, all of the windows are original, wood single pane. All have storms, I replaced about 1/3 of the storms with new Larson Golds I got from the depot. The others are ok but I plan to replace them all eventually. All the windows need new weatherstripping and glazing.
I sealed up a lot of cracks and gaps, but I find that the biggest issue is the floors get really cold which I attribute to the open balloon framing.

Think I'm going to have a mason come out and look at the foundation, see what he recommends. I have already air sealed and used foam board to seal up about a quarter of the rim joist pockets, which also seals off the open balloon frame stud bays. The basement is pretty dry, floor is concrete and mostly smooth but one section is very rough. With a good rain I will get seepage where the foundation and floor meet. Should I foam all the way down to the floor when I do it? There is some minor spalling inside on some parts of the first three courses of brick right above the fieldstones. Outside there is some that is limited to a corner where I need to fix a leaking gutter.

I've been finding that it isn't always easy to talk with installers. Some start out nice but don't seem to like being questioned. And they find out I have some knowledge they either get annoyed or uncomfortable. One was being intimidating, trying to tell me he's been doing this long enough and knows whats right for this house. All have told me "this such and such is the only brand I install", and that the small boilers won't support the radiaton. This same guy also said you need a boiler big enough to support heating the space AND the indirect water tank, even though I know you can have the indirect's zone on priority. Why didn't he know this?

You say the Burnham ESC is a good choice for cast iron, and UFT for modcon, what other brands are good?

 

John Molyneaux went through this process last year based on advice from this site, ended up with a contractor who installed Bosch mod-cons but his was the first house the contractor had installed the smallest-of-the-line version, and (apparently) was still a bit skeptical on the sizing despite both a Manual-J and fuel-use calculated heat load estimates that converged in a narrow range.[/QUOTE]

Yep. First, I had to defend why a boiler that was at least twice the size of my heat load would actually heat the house. Then they came back at me with "but you won't have enough hot water." Turns out I have plenty of hot water, too.

 

The fuel use load of 45,760 BTU/hr is an upper bound- at your boiler's age and oversizing factor I'd hazard that the real load (including the idling and distribution losses to the basement) is closer to 37,000 BTU/hr with the house as-is, but with more tightening, of the basement & attic plus insulation the load for that zone should come down to the 20-25K range even before insulating the framed walls. I'd hazard that as-is the total whole-house load is on the order of 50K right now, but will be under 40K with some judicious air sealing and insulating. If you do the whole nine yards including insulating & air sealing the balloon framed walls and tightening up the old windows it'll probably be in the 30K range for the whole house, not just the upper apartment. Most ~100K mod-cons have a min-fire output of about 30K, so you really want to think "smaller", keeping an eye on both the minimum and maximum firing rates if you hope to get the most comfort (& efficiency) out of it.

Just about any 50-80K input mod-con would work with your radiation, load, and zoning. As long as you're not planning to micro-zone it you have ample thermal mass in the radiation to work with. Stainless steel heat exchangers are plus, since they're less sensitive to system water chemistry. The Bosch Greenstar 57 that John Molyneaux went with is going to be enough boiler if you plan to actually tighten up and insulate the place more, lowering the load, could be marginal during extreme cold snaps if you don't fix at least the low hanging fruit on the building enveleope. The Triangle Tube Solo-60 is another popular stainless boiler that has good local support in many areas, and can probably cover you down to -10F or so with the house as-is. The stainless Burnham ALP080 would work just fine too, and just about maxes out what your radiation can actually deliver- anything bigger would be a waste, and possibly a mistake if it's min-fire output is more than ~15K or so if you're fixing the thermal losses of the house. I'm sure BadgerBoilerMN could come up with at least 5 more without having to think too hard.

It's fine to foam all the way down to the slab despite the seepage, but it sounds like you have some bulk water management issues on the exterior that are worth fixing even if you don't insulate. Grading the perimeter to slope away from the foundation, and directing the gutter output somewhere several feet away from the foundation would be a start. Without knowing the particulars of the yard it may or may not be necessary to dig in a surface drain along the perimeter on the exterior.

If you still get seepage after fixing the water management on the exterior, the common remedy which is more expensive, to be sure) is to install an interior side drain along the perimeter of the slab, directing seepage water to a sump:




Even if you're still balking about insulating the walls, at the very least verify that all of the tops of the stud bays are blocked, even if it's just cut-up cardboard boxes stapled into place. Some balloon framing uses NO top plates, others only on the walls supporting the attic floor joists, and many such houses have no top plates on partition walls too. All of this adds to the stack effect infiltration drives, and pulls a lot of air-transported moisture from the conditioned space into the attic. The attic floor and the tops of the framing have to be air-tight prior to adding more attic insulation, since the attic will be colder and more condensation/adsorption prone than it has been. Open cell foam is a fairly easy way to seal up the tops of plateless wall framing, but it's not the only way to get there.

The better-grade low-E Larsons are a good investment, and if there's condensation on the storms it's well worth tightening up the original windows too. The weatherstripping part is obvious, but may have to pull the trim to fully air seal the pulley & sash weight pockets, but there are also retrofit pulley seals that can take it down quite a bit. Caulking the trim to the finish wall and window unit when you put it back up is also an important detail. Replacing the clear-glass storms with low-E storms may be worth it at some point, but it's much lower on the priority list than overall house tightening.

 

Funny you mentioned cut up cardboard boxes, because that's exactly what they had over some of the open stud bays! Most of it disintegrated when I went to remove it to run new wiring. Some pieces of it dated to the 1940s. Only the center loadbearing wall and the outer walls in the attic have top plates, all of the interior partition walls, including the bathroom wet wall are open to the attic. Second floor joists are also open to the stud walls at the ends. I have sealed most of the open stud bays in the attic with foam board and spray foam, still have to do the wet wall yet. Also notice a lot of warm air coming through the 2" air space surrounding the chimney. Once I take it down I can cover up this chase and stop much of the stack effect. If I can say anything good about balloon framing, running wiring is a breeze!

I still would like to do the basement walls, just want to be sure any moisture won't affect the insulation and cause mold. Somebody already put fiberglass in the rafters and drywalled it. I don't think this was the proper way to do it (isn't there supposed to be an airspace between the insulation and the roof sheathing?) but not sure I want to tear down all that drywall and remove the insulation already there. First I'm going to finish air sealing and insulating the joist bays.

The house is on a narrow, 25ft. city lot as are all the other homes on the block. There is about 4ft on one side and maybe 6 on the other. I wonder if the houses being close together like this helps the heating load, or at least acts as a wind buffer.

 

Air sealing is the absolutely essential first step prior to insulating. If you don't, you'll have spots of wet insulation, and possibly moldy wood.

Any fiberglass insulation in the basement ceiling is not a problem- it can be left in place. Peel it back at the foundation sill & band joist so you can foam-insulate & seal that properly. Closed cell polyurethane is completely water proof to liquid water- at 3 lbs density it's used as walkable roofing in some commercial construction, and it will not support mold growth. It is only slightly permeable to water vapor, but at 2 lbs density and 2" thickness it is a Class-II vapor retarder- about as vapor tight as dry asphalted kraft facers on batts (but it's far more air-tight than most batt installations.)

Fiberglass between the rafters in contact with the roof deck IS a problem. Building codes call for 1" clearance combined with soffit-to-ridge venting if the fiber insulation is on the under side of the roof deck. If you're insulating at the attic floor peel the roof batts out. If they're not full of mold & mouse-poop lay them out and blow the new insulation over them. Under a layer of cellulose they run about the same R/inch, so as long at the top layer of the insulation is level, the R-value and performance will be pretty even.

It's legal to air-seal chimney chases using non-combustible materials if for some reason you opted to keep it. Cutting in some sheet-metal air-barriers and sealing it to the masonry with the appropriate fire-rated caulk works. You're not allowed to fill the 2" gap with insulation though, not even rock wool (which is extremely fireproof.)

 

The basement ceiling is bare, no fiberglass insulation between the joists. I've been air sealing the sill plate, and the gaps where the sheathing boards attach to the studs and sill plate. Then I've been cutting pieces of that 2" pink foamboard, fitting it between the studs/joists reasonably tight, and then spray foaming the edges. I went with two layers thick of the foam, just enough to close up the the open stud bays and then foaming around the edges.

In the attic I've been doing the same thing with tops of the open partition stud walls, using cut pieces of foamboard and then spray foaming it in. I also need to do the top of the bathroom "wet" wall, which is a huge open gap with lots of warm air coming up. Previous owner put the fiberglass in the rafters and drywalled it. I do plan to finish it off as a bedroom and bathroom so I would need the rafters insulated. Since the attic space will be finished off, I can't see insulating the attic floor except for the open balloon partition and plumbing walls. Much of the drywall job up there is sloppy so it was going to be removed anyway. I don't like fiberglass, and I figured on using foamboard here, maybe using 1x2 furring strips against the decking to create an air space, and foamboard over them and then spray foam the sides. The roof deck has the original 1x4 board slats over the rafters and new plywood decking over them. I also figured on using foamboard for the kneewalls, either that or Roxul, which I've used before and like.

I plan to take the chimney down to just below the attic floor, air seal and cap the top of the brick, and then patch and plywood over it. The space in the attic where it runs through is needed to put a bathroom in up there. In the lower floors it doesn't matter, the rest of the chimney where it passes through the lower floors could stay at least for now. It occupies space that's of little room value anyway. Unless taking the whole thing down and air sealing at each floor would be beneficial.

 

As long as the chimney chase is sealed at both the bottom and top the benefit of sealing it at intermediate floors isn't really measurable. Some people take the whole thing down to gain back several square feet of floor area though.

 

I will take it down to at least below the attic floor. In the apartments it's boxed in with built in hutches on one side. Too much work to open the walls up and remove it there and the space isn't of much use.

 

Wow!! You could make a TV show on this longest post. You're going to get a blast of very cold air this weekend (Valentine Day 2016) that those old puppies will be working very hard.
IN THE MEANTIME, GET A CARBON MONOXIDE DETECTOR FOR BOTH UNITS UNTIL THAT OLD CHIMNEY IS TAKEN CARE OF.