New boiler or strip heaters in existing heat pump air handlers

Mathelo

Question: Should I install a new boiler or add strip heaters to heat pump air handlers and add a HPWH.

Apologies but this will be a bit long winded and somewhat of a ramble.

We installed Bosch high efficiency heat pumps in the spring of 2022 (HSPF2 of 9.5). We have hydro-coils in the air handlers from the prior non-heat pump system that includes a 30-year-old boiler in the basement (also indirect hot water heater). Unfortunately, that 30-year-old boiler is failing (leaking) and I need to either replace it or have strip heaters installed in the air handlers for emergency heat. The idea of the strip heaters makes my skin crawl because I know they are an inefficient source of heat but that isn't logical thinking. I need to put some math to this.

I have determined that at our current oil/electrical rates and with the current boiler, break even using the heat pumps as the sole heat source is just below 20 degrees. The balance point is as low as 9 for the upstairs' unit and 18 for the downstairs' unit. Design temp for my area is 12 degrees. Average low temps here in Jan/Feb are just below 20. I’m in Stamford, CT (The southern edge of zone 5). Currently paying $3.66/gal for oil and will be paying $0.29/kWh for electricity effective 1/1/2023. Assuming the strip heaters don’t kick in until below 20 degrees, they should only see light use in Jan/Feb of each year.

Adding the strip heaters instead of a new boiler has some not obvious cost in my case. I will have to have an electrical subpanel installed to accommodate the circuit breakers for the strip heaters – probably a 5kWh (30 amp circuit breaker) and a 10kWh (2-30 amp circuit breakers.). I’ll also have the cost of adding the heat pump hot water heater. Some of this may need to be permitted, which is a hassle.

Even if the heat pumps with the strip heaters cost a bit more to run at these low temps, I'd be okay with that given the annual service requirements (over $500.00) for a boiler and it going out at least once a year. Getting rid of the boiler would be a benefit in multiple ways (freeing up space, no more oil, and getting pipes out of the untreated attic space) but having the boiler also has benefits including having some redundancy if one system breaks down.

As an alternative to going all electric, I can install a new more efficient boiler, currently considering the System 2000 Frontier EK1; also big upfront cost. This approach will take advantage of the fairly new indirect hot water heater and brand-new oil tank, and recently relined chimney. These are sunk costs that I shouldn’t fixate on but I would effectively be writing them off if I make the switch. I do, however, like having some redundancy in the event that one system goes out as has just happened with the boiler. And I should note that adding a boiler of this caliber should raise the operating temp breakeven cost point for the heat pump.

There is also the matter of the basement. It is a living space for a gym, general carpentry, and other tasks where temperature control has been less of a concern and taken for granted. It stays comfortable in the summer mainly as a result of leaky AC ductwork and similarly for the winter but I also have baseboard heating that is kept off. And the boiler is in the basement providing some heat. If I get rid of the boiler, I’m not at all sure how the basement will fair in the winter. It is only “half” underground.

Hope this effectively describes my situation. What would you do?

Replace the boiler with a new more efficient boiler or scrap it and go all electric?

If you got this far, thank you for reading and I’m looking forward to your responses.

Louis

Hot_water_fan

I’d do the strips - oil is already expensive and so are new boilers. Are you sure about the heat loss? 15kw of resistance on top of the heat pump output is quite a lot. If you do go the boiler route and you’re only using it a small fraction of the year, get the most basic one you can find - efficiency doesn’t matter as much as upfront cost for backup. Regardless, $500/year + a 5 figure installation price buys a TON of electricity. Another option is a propane furnace incorporated into the air handler. Either boiler or furnace, you’re slightly more redundant but still reliant on the same blower motor. 

As to the basement, a new boiler won’t be warming the place as much either - the waste heat is routed into the central or domestic water heating. 

For DHW, how much do you use? Plain resistance isn’t that bad if you have low consumption and a drain water heat recovery unit can get you about 40-60% to heat pump annual energy costs for a fraction of the upfront cost. 

You’re correct, all the previous expenses are sunk costs are should not be considered. Erase those memories . 

Steamhead

You can't go wrong with the System 2000. Those are nice boilers.

This job will be expensive no matter which way you go. You can put the strip heaters in later for redundancy.

Also don't forget- you can run the boiler off a reasonably sized standby generator- but you'll need a much bigger generator to run heat pumps or strip heaters.

Mathelo

Steamhead said:

You can't go wrong with the System 2000. Those are nice boilers.

This job will be expensive no matter which way you go. You can put the strip heaters in later for redundancy.

Also don't forget- you can run the boiler off a reasonably sized standby generator- but you'll need a much bigger generator to run heat pumps or strip heaters.

Good point on the generator.

Mathelo

Hot_water_fan said:

I’d do the strips - oil is already expensive and so are new boilers. Are you sure about the heat loss? 15kw of resistance on top of the heat pump output is quite a lot. If you do go the boiler route and you’re only using it a small fraction of the year, get the most basic one you can find - efficiency doesn’t matter as much as upfront cost for backup. Regardless, $500/year + a 5 figure installation price buys a TON of electricity. Another option is a propane furnace incorporated into the air handler. Either boiler or furnace, you’re slightly more redundant but still reliant on the same blower motor. 

As to the basement, a new boiler won’t be warming the place as much either - the waste heat is routed into the central or domestic water heating. 

For DHW, how much do you use? Plain resistance isn’t that bad if you have low consumption and a drain water heat recovery unit can get you about 40-60% to heat pump annual energy costs for a fraction of the upfront cost. 

You’re correct, all the previous expenses are sunk costs are should not be considered. Erase those memories . 

Oil is expensive but so are our electric rates. I'll be paying $0.29/kWh starting Jan 1st. CT has some of the highest rates in the country. So it can be less expensive running the boiler at certain temps.

Regarding the heat strip size, I'm assuming that when they kick in they are taking over heating responsibility from the heat pump. So I've basically added enough for a full load. Is that not the way it is done? My upstairs HP buts out 24,000BTUs and downstairs 36,000BTUs.

I had not considered adding in a propane burner. That is an interesting option for me to consider particularly since I already have propane for my stove and fireplace. I'm going to check this out.

Editing for a second thought here. Is it really a good idea to run propane into an attic since propane is heavier than air, a leak would collect down into the house.

WMno57

Mathelo said:

Apologies but this will be a bit long winded and somewhat of a ramble.

Louis, your decision making process and data is outstanding!
You will get a variety of opinions here at HeatingHelp from hydronics experts, people who care deeply about the environment, Engineers, common sense tradesmen, and me who is none of the above.
I'm the redundancy guy. I spent most of my career in Information Technology and Distribution. We had to keep computer systems up and get product to the stores, no matter what. I've designed redundancy for large complex systems and written disaster recovery plans. I've lived my entire life in cold places, love winter, and like to save money.
I believe in having both short term plans and long term plans. Skate to where the puck will be. Don't put all your eggs in one basket.
Indirect water heaters put two eggs (DHW and space heating) in one basket (boiler). Because indirects require the boiler to operate 365, I am not a fan. Short term it may, or may not make sense.
EK has great products and great customer service.
I have more thoughts on your decision. Really looking forward to this thread. Thank you for sharing this with us.

Mathelo

WMno57 said:

Mathelo said:

Apologies but this will be a bit long winded and somewhat of a ramble.

Louis, your decision making process and data is outstanding!

I can also suffer from analysis paralysis.

Jamie Hall

If it were me I'd go with the new boiler. As has been noted a couple of times, the running cost will be similar -- I'm also in Connecticut, and the electric rates are impressive, something which gets overlooked in other parts of the country.

However, in my analysis, it is for the redundancy and the ability to run the system off a generator. A common line of though is that well you don't have to worry about that because it is only a very few cold days when you need the heat. True. May I humbly point out, however, that it is those very cold days when you are most likely to have electricity fail -- such as the "blizzard" we had around here just before Christmas. That was not a one-off. As a neighbour of mine said, isn't it wonderful to have the generator and the oil burner! I don't have to drain my house and go to the warming centre! And she was quite rigth.

So for me -- boiler and oil, thank you very much.

WMno57

I like oil and I like having multiple baskets, but at some point it becomes hoarding (my collection of a dozen generators). Equipment is less likely to work when you need it, if it hasn't been used recently.
Since you already have propane, let's go down that path. How large of a propane tank do you have? If your tank is sized to run a boiler for couple weeks, I think that would get you through most outages.
Generac makes a good permanently installed standby generator. Runs on Natural Gas or Propane. I have the NG version. It gets the job done. There are small Diesel gensets, but they are uncommon, and harder to start in extreme cold.
Thinking you can cover all your bases with Electric and Propane. No need to maintain a tank full of Diesel Fuel.
Too bad you are so far away. I would offer to buy your used fuel tank if you were close.

Mathelo

Jamie Hall said:

If it were me I'd go with the new boiler. ... in my analysis, it is for the redundancy and the ability to run the system off a generator.

Are you on baseboard heat? I'm hydro into the air handlers so I'd also have to be able to run the air handler fans. I imagine that can be done with the generator but a bit different than just running the boiler.

hot_rod

Lp would be my choice. Maybe even a standard cast iron boiler. Maintenance will be less, you can shop off season rates, and you already have other appliances on lp add a second tank , or upgrade what you gave. And a lp generator could be an option.

Trade someone the new oil tank for a lp tank?

WMno57

Jamie Hall said:

As a neighbour of mine said, isn't it wonderful to have the generator and the oil burner! I don't have to drain my house and go to the warming centre!

Jamie lives so far north that his neighbors must be Canadian.
On the way to the Warming Centre they stopped at a Tim Horten's. They shared a dish of their favourite poutine with their neighbour who is a Councillor. They paid for their supper with a cheque, and stepped outside, where the northern lights subtly illuminated the grey colours of the winter snowscape.
Stay warm eh, and don't forget your toque.

Hot_water_fan

Oil is expensive but so are our electric rates. I'll be paying $0.29/kWh starting Jan 1st. CT has some of the highest rates in the country. So it can be less expensive running the boiler at certain temps.

Regarding the heat strip size, I'm assuming that when they kick in they are taking over heating responsibility from the heat pump. So I've basically added enough for a full load. Is that not the way it is done? My upstairs HP buts out 24,000BTUs and downstairs 36,000BTUs.

Oh no doubt electric at low COPs will be more expensive than oil. But if you’re paying $500/year for maintenance, that alone buys 1724kwh, plus however you want to divvy up the install price. Say it’s about $1000/year - that’s already 3500 kwh. Paying all that might not be worth saving a few bucks a year. 

The strips and heat pump should be running at the same time, so the strips needn’t cover the full load. Is the heat loss really 60kbtu?

Jamie Hall

WMno57 said:

Jamie Hall said:

As a neighbour of mine said, isn't it wonderful to have the generator and the oil burner! I don't have to drain my house and go to the warming centre!

Jamie lives so far north that his neighbors must be Canadian.
On the way to the Warming Centre they stopped at a Tim Horten's. They shared a dish of their favourite poutine with their neighbour who is a Councillor. They paid for their supper with a cheque, and stepped outside, where the northern lights subtly illuminated the grey colours of the winter snowscape.
Stay warm eh, and don't forget your toque.

Not that bad, c'mon. Though I have lived in the north country -- and love it! And my grandchildren are Canadian (born in the north). No, the recent example was northwestern Connecticut, and most folks in our area were without power for between 8 and 24 hours -- with a real temperature (not wind chill) of 2 F and 20 to 40 mph wind. No, it doesn't happen often. Yes, it will freeze your plumbing if you're not right there right now. Yes it will kill you unless you get to somewhere with heat. And just once on either of those eventualities will ruin your whole day.

Bottom line: don't count on your friendly electric utility to save your house or your life when it's really cold and nasty. They won't. They can't. It's up to you, individually.

On the air handler fans -- any reasonably sized household generator should be able to handle the fans. Or, in the country, the water pump. Or the freezers and refrigerators. Even an electric space heater (one). What it won't handle is a heat pump or an electric water heater, never mind electric strip heaters, unless you get one of the really big boys.

WMno57

The climate scientists will tell you these polar vortex storms will become more frequent due to climate change. I'm not a climate scientist. I guarantee we will have future winter storms, whatever their cause.
We are also at risk for power outages due to foreign bad actors.

Jamie Hall

WMno57 said:

The climate scientists will tell you these polar vortex storms will become more frequent due to climate change. I'm not a climate scientist. I guarantee we will have future winter storms, whatever their cause.
We are also at risk for power outages due to foreign bad actors.

Although there may be a good deal of politics involved, the bottom line is not political.

It's your life and your family's and your house. You, individually. Don't count on "them" to take care of the problem -- they can't, even if they wanted to. Have a plan and the means to safeguard yourself and your family -- on your own.

Mathelo

WMno57 said:

I like oil and I like having multiple baskets, but at some point it becomes hoarding (my collection of a dozen generators). Equipment is less likely to work when you need it, if it hasn't been used recently.
Since you already have propane, let's go down that path. How large of a propane tank do you have? If your tank is sized to run a boiler for couple weeks, I think that would get you through most outages.
Generac makes a good permanently installed standby generator. Runs on Natural Gas or Propane. I have the NG version. It gets the job done. There are small Diesel gensets, but they are uncommon, and harder to start in extreme cold.
Thinking you can cover all your bases with Electric and Propane. No need to maintain a tank full of Diesel Fuel.
Too bad you are so far away. I would offer to buy your used fuel tank if you were close.

Sounds like you are suggesting a propane boiler? I considered this (as well as a whole house generator) about a year ago and decided it didn't make sense. My current propane tank is 125 pounds. Way more than needed for our kitchen range but not near enough for a whole house generator or propane boiler. The plan was to have a 1,000 gallon tank put in but after considering the upfront cost and the fact that propane always costs more than oil, I decided against it. I needed a new AC so went ahead with the heat pumps. I've been very pleased with them so far. So propane really isn't an option other than for short duration use. Someone here suggested installing propane burners in the air handlers instead of the electric strip heaters but my research says that really isn't an option. I asked my AC support about this and he's never heard of it. If anyone can point me to a resource on this, I'd be very thankful.

Mathelo

Hot_water_fan said:

Is the heat loss really 60kbtu?

I performed a manual J using Cool Calc. My AC support confirmed I did a good job. Upstairs BTU requirement is 18,000 BTUs; first floor is 32,000 BTUs, and basement is also 32,000 but that one I'm not as comfortable with. So just counting upstairs and first floor, I'm looking at 50,000BTUs

Jamie Hall

50 K BTUh is 15 KW. 62 amps at 240 volts. Do you have the power in your main entry? In your switchgear? And how are you going to power those strip heaters when the power is off and it's really cold -- which is when you will need them. Just asking...

Mathelo

Jamie Hall said:

50 K BTUh is 15 KW. 62 amps at 240 volts. Do you have the power in your main entry? In your switchgear? And how are you going to power those strip heaters when the power is off and it's really cold -- which is when you will need them. Just asking...

If I lost electrical power, I'd be SOL.

Hot_water_fan

50 K BTUh is 15 KW. 62 amps at 240 volts. Do you have the power in your main entry? In your switchgear? And how are you going to power those strip heaters when the power is off and it's really cold -- which is when you will need them. Just asking...

Jamie, you're absolutely right - but he has a heat loss of 15 KW including the heat pump output, so it needn't be 15kw of resistance. Regardless, the opportunity cost of installing a boiler and paying an annual fee to maintain said boiler seems to me like it's not worth it. Should the power go off, run the heat pump off a generator + get a few more blankets. Maybe the house won't be 70, but the pipes won't freeze. Spend the rest of the money on something more enjoyable.

Jamie Hall

I always enjoy the cheerful assumption that the magic heat pump will keep up under extreme conditions. Maybe those once or twice a year conditions. Sorry. Nope. I'm running one now (a very good Carrier) as an experiment in part of Cedric's home, and at 2 F with a 20 mph wind... It wasn't keeping up, or even close, and was using every bit of 30 amps/240 volts from time to time trying. I know there are pricier ones which are alleged to work down to -10 or even colder (which we do reach, not often but every year two or three times), but until I'm forced to do it -- not happening. Cedric and the system he powers are oversized (Cedric isn't, but the radiation is) and the bottom line is that with a little 3 KW generator he can manage an 80 F inside to outside temperature differential, with the wind.

Mathelo

Jamie Hall said:

I always enjoy the cheerful assumption that the magic heat pump will keep up under extreme conditions. Maybe those once or twice a year conditions. Sorry. Nope. I'm running one now (a very good Carrier) as an experiment in part of Cedric's home, and at 2 F with a 20 mph wind... It wasn't keeping up, or even close, and was using every bit of 30 amps/240 volts from time to time trying. I know there are pricier ones which are alleged to work down to -10 or even colder (which we do reach, not often but every year two or three times), but until I'm forced to do it -- not happening. Cedric and the system he powers are oversized (Cedric isn't, but the radiation is) and the bottom line is that with a little 3 KW generator he can manage an 80 F inside to outside temperature differential, with the wind.

I was impressed with how well our heat pumps performed during this cold snap. Got very close to zero and the boiler was not helping (not getting water to the air handlers). But, the first floor unit could not keep up. It's balance point is just below 20 and it showed. Thankfully we have a honking big stove - close to 200,000 BTUs with all 6 burners and oven on. So that is our emergency heat when needed.

Roger

Great comments all around. Having a boiler and heat pumps allows the best in comfort and efficiency, and if electricity prices continue to climb, the boiler could play a more prominent role to minimize heating costs (or vice-versa). And with a boiler, you'd definitely be comfortable down at the lowest temperatures (assuming the system is properly designed). @Jamie Hall is spot on with generator backup as a further insurance policy protecting your comfort and home as grid stability and black outs are expected to worsen going forward.
Roger

pecmsg

Jamie Hall said:

I always enjoy the cheerful assumption that the magic heat pump will keep up under extreme conditions. Maybe those once or twice a year conditions. Sorry. Nope. I'm running one now (a very good Carrier) as an experiment in part of Cedric's home, and at 2 F with a 20 mph wind... It wasn't keeping up, or even close, and was using every bit of 30 amps/240 volts from time to time trying. I know there are pricier ones which are alleged to work down to -10 or even colder (which we do reach, not often but every year two or three times), but until I'm forced to do it -- not happening. Cedric and the system he powers are oversized (Cedric isn't, but the radiation is) and the bottom line is that with a little 3 KW generator he can manage an 80 F inside to outside temperature differential, with the wind.

Now, can you Start that heat pump

WMno57

I don't like the hydronic pipes going to the air handler through the unheated attic. Let's get rid of that.

• Option A
  
• 2 Propane Forced Air Furnaces in attic and basement for 1st and 2nd floors
  

• Option B
  
• New Boiler
  
• reroute hydronic lines to attic air handler through conditioned space
  

• Option C
  
• New Boiler
  
• new hydronic baseboard or wall radiators for 2nd floor
  

• Option D
  
• New small Boiler (heats basement and 1st floor
  
• Electric resistance baseboard for 2nd floor (emergency use, so efficiency not a concern)
  

Recommend smallest (not whole house) propane genset sized to run things you need (not elec res bb)
Recommend HPWH
I like option C the best. Probably the most expensive. New Boilers can be propane or Oil.

Hot_water_fan

Mine was modulating at 5 out and keeping inside toasty, but that’s just another anecdote. Regardless, we’re talking more insurance now and less heating. Probably better ways to provide insurance than either a boiler or a heat pump at this point.

Mathelo

WMno57 said:

I don't like the hydronic pipes going to the air handler through the unheated attic. Let's get rid of that.

It makes me nervous as well but they have been there for over 25 years and never a problem. They do have antifreeze. And I really dislike baseboard heaters. One of the first things we removed when we bought the house. Probably because we didn't grow up with them so we just hate them.

WMno57

I like @hot_rod suggestion for simple cast iron boiler. 90 /10 rule. 90 percent of time you will be running heat pump. 10 percent of time you will be running boiler. So lower efficiency not a big deal.

WMno57

• Option D-A hybrid
  
• New small Boiler (heats basement and 1st floor
  
• 1 Propane Forced Air Furnace in attic for 2nd floor
  

More expensive than D. Better 2nd floor heat than D. Heats basement better than A.

WMno57

Mathelo said:

They do have antifreeze. And I really dislike baseboard heaters.

I got this from another Wallie @JohnNY . I HATE GLYCOL. It makes a mess, it doesn't transfer heat as well, it rots boilers and equipment. Glycol is good in cars, bad in boilers. Two very different environments. BTW, there is no lifetime coolant for cars. Max of 5 year life. 2 years for traditional silicate green coolant. Glycol is a band aid for poor design in buildings.
There are now some new very stylish wall hung panel radiators.

SuperTech

I just want to add that the EK boiler can be easily switched from oil to LP by changing the burner.  The EK boilers with the Carlin EZ gas burner is super reliable and very efficient.  That's probably my favorite boiler regardless of fuel source. 

JohnNY

WMno57 said:

Mathelo said:

They do have antifreeze. And I really dislike baseboard heaters.

I got this from another Wallie @JohnNY . I HATE GLYCOL. It makes a mess, it doesn't transfer heat as well, it rots boilers and equipment. Glycol is good in cars, bad in boilers. Two very different environments. BTW, there is no lifetime coolant for cars. Max of 5 year life. 2 years for traditional silicate green coolant. Glycol is a band aid for poor design in buildings.
There are now some new very stylish wall hung panel radiators.

I said all that? I don't think so.

WMno57

Sorry @JohnNY . I did not type that clearly. I think about a year ago you said "I HATE GLYCOL". I recall you said it was due to mess, heat transfer and rots. The car stuff and poor design band-aid are my opinions.
Glycol in hydronics is somewhat OK if it is maintained every year. The included inhibitor additive package MUST be compatible with everything in the hydronic system, and the local water.
DexCool is a great ethylene glycol for cars with aluminum engines and radiators. Except for the one GM V6 model that had intake manifold gaskets incompatible with DexCool's Organic Acid Technology inhibitor package. GM had control of and knowledge of everything in their line. They had testing labs and thousands of engineers. GM still screwed up.
How could a contractor possibly know if the additive package of their locally available propylene glycol is compatible with everything in an existing hydronic system? How would they even know compatibility with a soup to nuts new system where they spec everything?
So yes, I believe Glycol should be avoided in buildings and hydronic systems if possible.
https://en.wikipedia.org/wiki/Antifreeze

WMno57

Almost forgot. The inhibitors wear out and must be refreshed.
I HATE GLYCOL

WMno57

JohnNY said:

I hate glycol.
I hate glycol.
I hate glycol.

I hate the smell. I hate the sticky. I hate the buckets. I hate the refractometer. I hate the cost. I hate the calculations to get the right mixture. I hate maintaining the mixtures. I hate having a leak.

I just finished a system that took over 200 gallon of Cryotek to get to a 30% mixture. A Hoffman 79 in the middle of the system leaked and drained 4 stories of my mixture into a floor drain. Getting this right again is a nightmare of cost and effort.

Avail yourself to as little involvement with glycol as you possibly can. Trust me.

Edited to add:
Only about 25% of that system was vulnerable to freezing. After the last big loss event, I got the engineers to agree to add a heat exchanger. Now, my portion of the system is 100% water and only the HVAC company's portion which supplies heat to rooftop air handlers is filled with 30% glycol.

WMno57

Increased viscosity requires more pumping power. More wear and tear on pumps. Pretty sure my 75 year old boiler and 105 year old pipes and radiators have never had any glycol or inhibitor.

Mathelo

WMno57 said:

Almost forgot. The inhibitors wear out and must be refreshed.
I HATE GLYCOL

So how do you feel about glycol?

So is it even possible to adequately insulate the pipes in the attic so antifreeze isn't needed? Incasing all pipes in a thick layer of foam maybe?

pecmsg

Mathelo said:

Almost forgot. The inhibitors wear out and must be refreshed. I HATE GLYCOL

So how do you feel about glycol? So is it even possible to adequately insulate the pipes in the attic so antifreeze isn't needed? Incasing all pipes in a thick layer of foam maybe?

Insulation slows the transfer of heat, doesn’t stop it. Sooner or later it will freeze!

Jamie Hall

Mathelo said:

WMno57 said:

Almost forgot. The inhibitors wear out and must be refreshed.
I HATE GLYCOL

So how do you feel about glycol?

So is it even possible to adequately insulate the pipes in the attic so antifreeze isn't needed? Incasing all pipes in a thick layer of foam maybe?

Depends on how cold it gets and for how long, and if the system is running. If the system is running (pumps on) and the boiler is keeping up, they will only freeze in really extreme conditions -- continental US doesn't get that cold (northern prairie Provinces, northern Ontario and Quebec, inland Alaska do!!). But if the water isn't flowing, then insulation will delay things -- but won't keep them from freezing if it's cold enough long enough.

HVACNUT

When it's time to replace my CAC, it will be with a heat pump. 
When it's time to replace my boiler, it will be an EK-1 Frontier. 
It will be staged. Not sure if I'll wire it to fire the boiler during defrost mode. We'll jump off that bridge when we get to it.
@Mathelo, if you decide on boiler replacement rather than eliminate it, the EK-1 is easily converted to natural or LP gas if that's ever a better option down the road. 
If you want to go a different route, last month I installed electric resistance heaters in an air handler for a client who has solar for electric, but wants to use every kw he's got rather than get back one sixth of what he paid for it.