Difficulty in Properly Sizing Equipment - 2140 Sq Ft New Construction Spray Foam House
Hi All and thank you for allowing me to join the group.
I am starting the process of building a new construction 2140 square foot 2.5 Story 2.5 Bath Colonial home that has some space restrictions (no cellar and no garage) in Suffolk County Long Island NY. That said all utilities will have to go into an attached 9' X 10' 6" one story utility room (also have a little room for A/C ductwork & equipment in the attic space).
- With some help from the great experienced guys on this site I decided to go with: an Energy Kinetics EK-1 Frontier Oil fired boiler with Stackable 40 Gal Indirect Water Heater. I'm told its an excellent reliable boiler with capability to be converted to natural gas if they ever bring gas service in to my community… Wanted to use a standard stainless steel chimney stack to remove potential failure of direct vent fan in the future (figured one less moving part to fail?) I also decided on Oil heat because we have no Natural Gas in the area and I happen to like the folks at my local oil company. I plan on doing two zones of hot water cast iron baseboard or fin tube, and two additional zones of radiant floor in Kitchen and second floor baths. Ran a heat loss calculation as advised by guys here and the new house when spray foamed and with Anderson 400 series windows looks to **only call for 39,000 BTU of heat**. The EK-1 Frontier with its factory .85 nozzle produces 100,000 BTU's of heat. and that nozzle is required for top chimney vent according to the helpful folks at Energy Kinetics. I don't want a condensating boiler and Most standard cast iron non-condensating boilers also seem to also produce about 100,000 BTU so almost everything out there looks oversized for my home according to this heat loss calculation (attached below)… Will this create a problem with short cycling or other problems?
2. As far as the HVAC is concerned I am leaning towards going with: Two zones of either 1stage or two stage ducted A/C with Heat Pumps (to handle shoulder seasons), Whole house Dehumidifier and an Energy Recovery Ventilator for fresh air…
-Problem here looks to be the BTU Cooling load came in at only 29,000 BTU for the entire house with spray foam and tight construction.
-I would like two zones: one for first floor living space which is 1160 sq and the other zone for second floor living space which is approximately 980 sq. Total home = 2140Sq Feet
Thoughts on good units and best way to accomplish this? The 1.5 ton units look to be 18000 BTU and 2 ton Units are 24,000 BTU's. I want simple to service, reasonably priced, reliable equipment for the long run, but concerned with the oversizing of equipment that so many people with lots of working knowledge and hard earned experience have talked about on this site… Thought to possibly use two stage either 1.5 ton or 2 ton equipment for each floor might help with the oversize when running at 60% capacity most times in first stage but not really sure if that's the right way to handle this?
Any thoughts/help would be greatly appreciated!
Comments
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That is a problem with Oil Heat equipment. The smallest input Equipment is often too big for the building. That said, the EK has the best control to reduce the short cycling associated with oversized equipment. So explain your concerns to the nice folks at EK and they will help you to design a great 2 zone system.
And the thing about 1.5 ton cooling as the smallest available… There are some Variable speed inverter outdoor units that are usually associated with MiniSplit systems that can be connected to 1.5 ton ducted air handlers. some of the match ups are as small as 12,000 BTU or 1 ton. Ask your HVAC contractor to look into this option from their local supplier. I know that Fujitsu had one available several years ago before I retired. I'm sure the other brands have also joined in.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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minis have low static ducted units that are 1-Ton or less.
Please
2 stories
2 systems.
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For new construction, done to current code, in your climate, 2140 square feet, 39K heating and 29K cooling actually sounds kind of high.
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Thank you for your post, @2Luckysat . Energy Kinetics boilers with thermal purge (energy recovery) have virtually no oversizing penalty, so you’ll have exceptional recovery for hot water with the full capacity the boiler and you don’t have to worry about lower efficiency in load heating load situations. There are a few ways to tackle your planned radiant zones, although we like to use a storage tank to provide the best efficiency and operation overall. Please have your installer reach out to us so we can coordinate with them to propose a design that will work well with the tight space you have for the mechanical room.
I read a recent ASHRAE article comparing a ducted air conditioning/heat pump system with a ductless mini split system with the same “hangtag rating“. The article indicates higher effectiveness of dehumidification and lower overall energy consumption for the ducted system. I found an accessible copy of the article (or a similar one) here if you’re interested in finding out more:
https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=3320&context=iracc
Best,
Roger
President
Energy Kinetics, Inc.
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What are your local utility costs? Around me oil is about 3x the operating cost of a heat pump so it makes no sense for a new build.
You area already adding ducting for AC, so your additional cost is only the up charge to a heat pump which will be a fraction of the cost of oil tank, boiler, plumbing and rads.
18/BTU per sqft in zone 4 sound very high for a tight new construction. I would doublecheck the manual J assumption as something is off. It should be closer to 8-12btu/sqft.
Even assuming 39k is correct you could heat the house with a combination of:
https://ashp.neep.org/#!/product/64682/7/25000/95/7500/0///0
and
https://ashp.neep.org/#!/product/64684/7/25000/95/7500/0///0
These are modulating units, if you look at the turndown on cooling it is pretty decent so even though it is oversized for cooling load, it should still turn down enough.
My guess once you get your manual J dialed in, a single 2 or 2.5 ton cold climate heat pump can heat and cool your place without issues.
Bonus of a heat pump is the SEER rating on it is much higher than your typical AC, so your cooling costs will also be significantly less.
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Looking at the published rates for Suffolk County at:
it seems complicated, but it looks like if you're all-electric in winter you pay a delivery charge of 5c per kWh and a power supply charge of 11.75c or a total of 16.75/kWh.
At $4/gallon, fuel oil costs about 4 cents per 1000 BTU or 13.6c per kWh.
If your seasonal COP is higher than 1.2 the heat pump is going to be cheaper. Design temperature for Suffolk County is 10F, a Mitsubishi HyperHeat has a COP of 1.93 at 5F and at 47F it's 4.4.
I wouldn't be surprised if the heat pump has half the operating cost of an oil boiler. And as @Kaos notes, if you're already installing air conditioning the additional cost of heat is nominal.
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Interesting points. I think you’ll find that the Energy Information Administration shows NY at $0.25/kWh or about $10/gal equivalent and Long Island is not on the low end for the NY rate structure. You can also see the rapid escalation in the price for electricity over the past several years. This indicates that it’s wise to have a hybrid system so you can always choose what’s best for your own needs for efficiency, cost to operate, comfort, reliability in the winter, and/or emissions. This boiler will also last 3 times as long as a heat pump, and can run on 100% biodiesel for exceptionally low carbon intensity.
President
Energy Kinetics, Inc.0 -
Comparing input costs and not output costs doesn’t help people make decisions here. Let’s stick to output. Dual fuel might still be the move, but input costs are misleading.
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That's the statewide average. Suffolk County has a special winter rate for all-electric houses.
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Thanks Roger,
Your reputation speaks for itself, and you are definitely running a great company over there at Energy Kinetics. I was able to speak with John Hachmann from your place a couple months back and he couldn't have been nicer. The idea is I just want a simple reliable boiler for my home. With the tight space in that utility room 9' x 10'6" I was thinking your Frontier EK-1 with stackable 40 Gal indirect water heater and top chimney vent with stainless steel liner?
-The house will most likely end up with 2 zones cast iron baseboard (one for first floor & one for 2nd Fl) if budget permits, if not then fin tube baseboard… With two additional zones of hydronic radiant floor heat for the kitchen and two upstairs baths which will be tile floors…. So a total of four zones hot water heat & 1 zone for the stackable indirect
-Also wanted to know best size diameter of stainless steel liner for the Frontier EK-1?
Does this sound like a good set up to you?
-I know people have different opinions on the A/C as well… Same idea there I just want some simple reliable equipment. Ideally two seperate single stage basic 1.5 ton units (they don't seem to make anything smaller) and this spray foam seems to almost make a house too damn tight… One for first fl & one for 2nd fl with capability to add heat pump and dehumidifier. Thoughts on that?
-Lastly do you know a good place to get a proper Manual-J calculation done? I have a set of plans & did my own calculation on the internet but guys said it may be off. Would like to know BTU's for home, feet of baseboard required for each room and proper A/C ducts/diffusers for each room.
All this new fancy stuff has me nervous because it's pretty hard to understand and looks expensive to repair. My current home is only 1000 Square feet with a basic inexpensive two ton single stage Reem unit. It's over 13 years old, cheap on electric for the months we use it and runs great… I don't know why the new home I want to build has to be so much more complicated.
Thanks for all of your time
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I don't know why the new home I want to build has to be so much more complicated.
ha because you’re installing a luxury heating system !
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Thank you for your kind words and confidence in Energy Kinetics, @2Luckysat .
The stackable Frontier EK1 is an excellent choice based upon your description. Because your home is will be so tight, it may be under negative pressure; for that reason you may want to consider a sidewall vented version, which will also save the chimney costs. The vent fan is quiet and should last a long time, it does not add significant complexity as there is only on additional proving switch and the fan motor. Today's oilheat is ultra low sulfur fuel which means boiler scale buildup is virtually eliminated. Going in the natural draft chimney direction (at least 10' high), we recommend a 5" corrugated metal liner although a 6" liner would also be more than adequate.
I think that it makes sense to install a heat pump for anyone replacing or installing a new AC system. The hybrid solution with a boiler and high efficiency water heater affords great flexibility and peace of mind in a potentially uncertain energy future. I agree with your two zone approach as well. For some extremely tight homes (near the passive house standard for heat loss); I saw a presentation where PVC was connected through rooms with a bathroom fan to redistribute the heating/cooling effectively with a single heat pump; the key in all applications is to make sure that distribution is adequate make all rooms similarly comfortable.
For the heat loss calculation, your heating and AC pro should be able to provide the calculations. As you mentioned John Hachmann, I'm sure he can facilitate your request if needed.
Adding further detail for @DCContrarian , after 400 kWh consumption, the all electric rate drops by about $0.04/kWh for PSE&G Long Island (see this link). @Hot_water_fan , good comments regarding output - one of the best sources and analysis that takes into account many field performance studies of heat pumps can be found here. This demonstrates that high efficiency cold climate heat pumps operate at a COP from about 2.0 to 2.5 at 30°F, and efficiency drops further as temperatures fall (a COP of 2, or 200% efficiency would lower $0.25/kWh to $0.125 or about $5.00/gal of oil equivalent; this compares to oil at $3.50 per gallon at 85% efficiency or $4.11 equivalent - a lower cost to operate with added comfort and quietness of operation). This reinforces the hybrid solution for heating economy, comfort, and emissions reductions with an efficient boiler and biodiesel blends.
Best,
Roger
President
Energy Kinetics, Inc.1 -
@Roger good catch with the electric heating rates!
@2Luckysat from the PSEG website
- The October PSC rate is $0.11751/kWh
- The delivery charge for consumption >400kwh a month is $0.0534/kwh
- Combined, supply + delivery is: $0.17091/kwh. At a seasonal COP of 3, you're paying about $16.70/MMBtu.
- With EIA's NY heating oil price at $3.67/gallon, with COP = .85, that's $31.34/MMBtu, 88% more.
- Obviously all of these prices will change.
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Thank you, @Hot_water_fan - I'm sure these prices will changes as you note.
For reference, I just looked at a Suffolk County statement for a Long Island PSE&G residential electricity bill and Delivery and System Charges include "certain transition charges" and other fees that raise it to $0.13/kWh; adding in power supply charges, taxes and other charges brings the total rate to $0.27/kWh. The All Electric heating would reduce this rate for purchases over 400kWh by about $0.04/kWh; some of the other charges are fixed, so the bill is likely to be about $0.23/kWh at these rates, or $9.34 per gallon equivalent ($3.74 to $4.67 per gallon at a COP of 2 to 2.5 which is reflected in field performance at 30°F outside, but higher priced at lower temperatures).
Roger
President
Energy Kinetics, Inc.0 -
For reference, I just looked at a Suffolk County statement for a Long Island PSE&G residential electricity bill and Delivery and System Charges include "certain transition charges" and other fees that raise it to $0.13/kWh; adding in power supply charges, taxes and other charges brings the total rate to $0.27/kWh.
Can you please link to this? I'm seeing $.0534 - where are you finding the other $.08/kwh?
The All Electric heating would reduce this rate for purchases over 400kWh by about $0.04/kWh; some of the other charges are fixed, so the bill is likely to be about $0.23/kWh at these rates, or $9.34 per gallon equivalent ($3.74 to $4.67 per gallon at a COP of 2 to 2.5 which is reflected in field performance at 30°F outside, but higher priced at lower temperatures).
$/MMBtu delivered is so much easier to understand for me :).
It's interesting how few hours under 30F (well HDD base 65 >= 35F) Long Islands experiences.
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@Hot_water_fan , this is from an actual bill, not from an online source. The notable difference in the published rates is that General use is $0.0972/kWh Oct-May and residential home heating is $0.0534/kWh for the amount over 400 kWh. The Electric Heating rate sheet notes that following - Power Supply Charge: 100% of monthly published rate.
Roger
President
Energy Kinetics, Inc.0 -
@Roger Can you post it? I wish utilities could make this easier :)
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There's a line that indicates 51% of the bill is delivery and system charges. Here's the detail:
The cost to deliver electricity: Includes operation and maintenance of the electric system and certain transition charges of $0.021306/kWh on behalf of the Utility Debt Secularization Authority, the owner of such transition charges.
Then there is 8% of the bill for Taxes and Other Charges, so the net is only 41% of the bill relates to Power Supply Charges.
President
Energy Kinetics, Inc.0 -
Maybe easier this way?
Total kwh = ?
Total cost = ?
Total charges not billed by the kwh = ?
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For heating what you care about is the marginal cost — how much the bill goes up when usage goes up. Lilco has pretty hefty fixed monthly charges that are there regardless of how much you use.
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@DCContrarian no doubt! What I’m hoping to see is total marginal $/kwh. There may be a chance that in-floor electric heating + heat pump gets the warm toes + central heating without a boiler and avoids building/ downsizes the utility shed. That could save 5 figures and be cheaper to operate too. The rationale for heating oil here isn’t that clear.
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Not on the Isl of Long!
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@pecmsg post an electric bill! I’m shocked too, but the rates aren’t as high as expected. I’m not ruling another heating source in addition to the heat pump, but oil looks bad here because it’s
1. Expensive to operate
2. Expensive to install due to its relative size (tank plus boiler) that either itself necessitates or contributes to needing a utility room.
3. Doesn’t provide ancillary benefits like propane, gas, or wood could.
So why oil here?
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Right now, oil is 2.50 - 3.50 per gal. on the east end.
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@pecmsg quite the range! What's the electricity rate? Looked like
October Supply $0.11751/kWh + Delivery & System Charges $0.0534 for rate schedule 580, with other charges to be disclosed by Roger hopefully.
Hard to make oil work with those numbers with that heat loss unless someone installs the boiler for free.
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I’m paying .27 kw
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can you post an anonymized bill?
But as you know, even $.27/kwh basically matches oil at $3/gallon. So again, given that AC is being installed, why oil? Propane or wood + electric seems like they provide more for lower install costs. This is a new, pretty efficient house maybe we can make this less complex?
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when I get home
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Just to reiterate, $0.27/kWh is the equivalent of oil at almost $11/gallon. Since high efficiency cold climate heat pumps operate at a COP of 2.0 to 2.5 at 30°F (see prior post), that's significantly more than today's oilheat prices. Electricity would need to be about $0.17/kWh to $.021/kWh to compete favorably with $3.00/gal oil at 30°F (COP of 2.0 and 2.5 with 85% efficient boiler).
President
Energy Kinetics, Inc.0 -
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@Roger - I think your math is just off somewhere. Let's do the prices in terms of 1M BTU.
- In terms of energy, 1M BTU/3,412=293 kWh for electricity or 7.22 gallons of oil (138.5KBTU/gallon)
- At $0.27/kwh, that gives us $79.11 with a COP of 1, $39.56 with a COP of 2, $26.37 with a COP of 3
- With a boiler efficiency of 85%, that would require 8.5 gallons of oil
- For the HP, that then gives us the equivalents:
- COP of 1.0 == $9.30/gallon
- COP of 2.0 == $4.65/gallon
- COP of 3.0 == $3.10/gallon
To get $11/gallon, you would need a COP of 0.85 (which is what you're claiming for the boiler, not the heat pump, and where your math is probably off).
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no but it makes his boiler that much more efficient!
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$/MMBtu output is the way!
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rough #,s
2700
7900
https://coalpail.com/fuel-comparison-calculator-home-heating
with a COP of 3-1 even.
the colder it getsThe lower the COP
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@pecmsg ?
We want $/MMBtu output.
Regardless, that's point 1.
Point 2 is the install cost of this heating oil boiler. Let's say, for the sake of argument, the boiler is cheaper under 30F, say $10/MMBtu cheaper. A house with a 39kbtu heat loss will use about 80 MMBtu/year, so ~26MMBtu will be under 30F on LI. We won't discuss prices, but that's a lot to spend to save roughly $260/year. With propane or natural gas, you can use it for cooking. Like wood, you can also use these for ambiance. Oil doesn't meet those needs. A propane EK could be a great choice instead!
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Thank you, @fentonc - we're doing the same math.
Electricity at 3,412BTU/kWh and oil at 138,700 BTU/gallon yields $0.27/kWh / 3412 BTU/kWh x 138700 BTU/gal = $10.97 per gallon on a per unit of energy basis (almost $11/gallon as I noted). I adjusted later for the efficiency of the heat pump and boiler to make a comparison that is easy to understand in units that people are used to seeing (dollars per gallon in this case). The equivalent cost per gallon goes up for an oilheat system at 85% efficiency ($3.50 becomes $4.11), and the cost per gallon equivalent of electricity goes down for COP of 2 ($10.97/2 or $5.49 or $4.38 for a COP of 2.5).
President
Energy Kinetics, Inc.0 -
People tend to overestimate how cold a place is and how long it stays cold. In most places, most of your heating energy use is when the outdoor temp is well above your design temperature. Most places spend so little time at design temps that efficiency at that point simply doesn't matter.
The one number ratings are not the best but in this case the HSPF2 typically shown is for zone 4 which is the OP's area. If you look at the Carrier units I linked to earlier, their HSPF2 is 9.3 and 10. That works out to a seasonal COP of 2.73 and 2.93*. Assuming the units are sized properly, you should be able to hit that with a heat pump install.
I'm in colder climate with cheap electricity and reasonably priced natural gas. If you include the cost of meter fees, the operating cost of a heat pump VS gas is about the same.
*HSPF2 ratings assume restrictive ducting representative of typical install. If you spend some time and design those well, you get even higher efficiency for minimal cost increase.
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@Kaos likewise, in MD gas also loses out to electricity. Dual fuel is great if you’re going from existing Gas + AC to existing gas + HP. The other permutations face more challenges.
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For your approval:
I've created a spreadsheet that models the annual electricity use for a Mitsubishi HyperHeat heat pump, in Suffolk County, for heating. Rated capacity is 54,000 BTU/hr at 47F. I used the 39,000 BTU/hr design load that @2Luckysat provided.
You can view the analysis here:
The tab labeled "Summary" shows the performance at each temperature between 60F and the design temperature. The calculated weighted COP is 3.1.
I used the performance data from the Neep.org site at:
https://ashp.neep.org/#!/product/156628/7/25000/95/7500/0///0
to create the performance curve that is in the tab labeled "Performance Curve," and is the basis for estimates of output and COP.
The climate data — hours per year at each temperature — also comes from Neep.org and was measured at Grabeski Airport.
I also did a similar analysis with a smaller HyperHeat unit,
https://ashp.neep.org/#!/product/156607/7/25000/95/7500/0///0
That is only rated for 40,000 BTU/hr at 47F and therefore is somewhat undersized. At temperatures below 15F it would require backup resistance heat and 1.5% of the annual heating load would have to come from backup heat. However, the smaller unit would run in a more efficient part of its range for more of the heating season, so the seasonal COP is higher — 3.4 vs 3.1 — including the electricity used for resistance heat.
What this shows me is that when it comes to looking at heat pumps, simple rules of thumb are somewhere between useless and harmful. To really get a picture of the energy usage you have to analyze a specific piece of equipment, in a specific house, in a specific location.
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My estimate is that the annual electricity use for heating would be 7961 kWh.
In most of the Northeast you can expect the equivalent of about 1000 hours of direct sunlight a year. So an array with a rated output of 8000 Watts would meet the heating needs for a year. I'm seeing installed pricing of about $3/watt for solar.
I would suggest that the installed cost of a HyperHeat heat pump and a solar array to power it would be less than the installed cost of an oil boiler, radiators, and air conditioning.
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