Expensive electric combo boiler or cheaper electric boiler + water heater?
I’ve been siphoning off valuable information as a non-member for ages now, but no one seems to have spoken online about my current situation, so I’m happily forced to join the movement!
I’m contracting the build of my Southern Ontario as-close-to-Net-Zero-as-possible house, and have been left with two wildly disparate quotes from HVAC contractors to take care of my hot water needs. The system will be electric boiler-driven radiant floors throughout the 3200 sq. ft. home (wood stove backup), with accompanying HRV.
One contractor has recommended the Combomax Ultra 50, which is a combined boiler and on-demand DHW heater. This install, while definitely state of the art, will cost $23,000, not including the in-floor pipe supply/install, which I will be doing myself to save $. The other contractor has recommended a Benjamin Aquastar 12kW boiler, and to just get a conventional hot water heater to take care of DHW so he will not be part of that install. His price: $9600 (plus the incurred cost of purchasing/installing a HWH which I don’t yet know).
What do I do? I don’t know if I can afford the first guy, although I don’t want to cut corners on this part of the design. Is he gouging? The other guy is so cheap, can that boiler perform to Net Zero standards? If I install the Benjamin, will I sacrifice Net Zero? If I install the Combomax, will I ever make up the premium in energy savings? It’s a tough call – if anyone has any insight I would highly value it.
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Replies
Jason,
I just finished answering another question about using electric resistance heaters to make hot water, and then circulating the hot water through PEX tubing for space heat. You might want to read that thread: PV Hot Water & Radiant Heating System.
I'm not a fan of the approach you suggest. If you want to heat with electricity, why not just install a few ductless minisplits or ducted minisplit units?
Alternatively, if you want to heat with electric resistance heaters -- an expensive system to run, but a possible approach -- why not just install a few electric-resistance baseboard units, and skip the PEX tubing and hydronic circulators?
To answer your question: There is no way I would accept the $23,000 bid, especially in light of the fact that the bid doesn't even include any hydronic distribution system.
There is no way to say that the 23k price is too much . We do not know what he is including nor do we have another bid for a like system to compare to . Does that price include tubing layout and system design in order for you to offer your sweat equity ? Although you are doing the tubing , this contractor still has to warrant and repair any system flaws . He will be married to a system which he did not do the complete install . That comes with a price attached , as it should . Canada also has requirements and pay scales that put everyone on a level playing field .
I would definitely disqualify the guy offering a simple electric resistance water heater for almost 10,000.00 .
Richard,
Canada has what?
Not really in the mood or mindset for a political discussion Malcolm . Canada has a very strict requirment for hydronic system design and install . There is also a structure in place which shows very close pricing from shops who follow the rules and do things right .
You may have different experience and that is to be expected since there are backdoor operators there as well as here . My experience however is completely based on associates and aquaintances in my circle of professional designers , installers .
When first cost is more of a concern than quality and when folks think they can receive quality at a cheaper price than what most charge , they indeed become prey items for the unscrupulous . That exists everywhere .
Hi Martin and Richard,
Thanks for your answers - I should probably provide some more details: I will have a 10 kWh PV array to offset the cost for running the boiler, so that is not an issue. We're also going to have significant passive solar heat coming in our windows, so heating loads are going to be minimized. I have considered minisplits and while they are great products, we prefer radiant heat over forced air, and air-to-water heat pumps are not adequate for our climate. Net Zero homes have succeeded with the type of system I'm describing, so their efficacy is not the issue. Also, both contractors will be supplying and installing the HRV system, which I failed to mention. The pricey one will install an VanEE and the cheap one will install a Lifebreath - both good brands so I'm not fussy about which one.
In any case, my question is about whether it's worth the price to install the Combomax, or if I can achieve the same results with an electric boiler + HW heater. If anyone has experience with the Combomax, feel free to chime in.
Richard just FYI the $10k install was for the boiler not the HWH. And the HRV.
http://www.nextgenboiler.com/ with a TurboMax would be nice . Maybe someone may be up to the task .
ComboMax would be my choice . You'll also be able to hold the electric out for a bit also if you used a Taco I Series mixing valve with ODR . One of these installers seems to know about mass and how to use it , I think .
Remember , you don't get what you don't pay for . Slight twist there but all too true .
I have a different view than Martin . LifeBreath , boiler and water heater for 10K does not sound like enough money for that job . How does this guy make money , does he know how much to charge , will he be around to service since it appears he very well may not ? Even thief contractors who are terrible charge enough money for the job , this may very well be a contractor whom just does not recognize the value of his work , a gamble at best .
Jason,
You wrote, "I will have a 10 kWh PV array to offset the cost for running the boiler, so that is not an issue."
I disagree. If electric-resistance heating requires between twice and three times as much electricity as a heat-pump system, then those costs will dog you for the life of the system. Buying a 10-kW photovoltaic system doesn't make your electricity cheaper -- it just means that you're buying your electricity in a lump sum instead of paying by the month.
It's your house -- but electric resistance heating will always cost more to run than a heat pump.
Jason, you initially asked "If I install the Combomax, will I ever make up the premium in energy savings?" The answer to that is no. Both systems are electric resistance heat. They both have the same terrible efficiency. In your climate, you can still benefit from a cold-climate-capable air to water heat pump such as the Chiltrix system, even if you want to have a resistance heat backup in place. Then you would have the ability to make up the premium in energy savings.