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Electric Boilers and DHW production

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SoCal_Hydronics
SoCal_Hydronics Member Posts: 9
edited January 2023 in THE MAIN WALL
Greetings,

I am sure I am not alone in being asked, quite often now, to provide all electric heating + DHW systems. Our region has natural gas infrastructure and NG is MUCH less expensive per KW than electricity. Even after carefully explaining the advantages of modern gas modcon boilers to highly educated individuals, they still express the desire to go electric. Science doesn't seem to have much to do with their decision -making. This seems to be a trend the last couple years... given the folks I see driving around masked in their cars, as well as biking, skateboarding -- you get the picture. This is California after all.

Anyway -- Viessmann has introduced a new electric boiler line. The largest output model draws about 70 AMPS and produces 49MBH. I have a job where my radiant heat loss is about 40 MBH (so far so good) and I would also like to provide DHW via an indirect. 49MBH and an 80 gl tank would probably provide enough recovery for the 2 bath residence, but the boiler has a 140° output limit. This is a bit limiting to heat up a tank. Also, the boiler does not have separate HHW and DHW TT terminals and corresponding output temps -- so I would have to work around that.

I am interesting in hearing from other professional as to how they would go about providing all electric HHW + DHW in this scenario.

Thanks!

Comments

  • Hot_water_fan
    Hot_water_fan Member Posts: 1,897
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    For DHW, why not a tank? I see no advantage to an indirect. Indirects are pretty unpopular in the US. For heating, an air to water heat pump would be great in a California climate. 
    ethicalpaulSolid_Fuel_Man
  • hot_rod
    hot_rod Member Posts: 22,327
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    This product has some interesting applications for all electric hydronic options.

    https://www.thermo2000.com/en/products/combomax-ultra/
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SoCal_Hydronics
  • Jamie Hall
    Jamie Hall Member Posts: 23,524
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    Much better -- and much cheaper to run! -- use a heat pump water heater for the domestic hot water, and an air to water heat pump (several good makes) for the radiant heating. The latter do have limitations on the maximum temperature they can provide, but you can easily get around that with adding some radiation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterManethicalpaul
  • SoCal_Hydronics
    SoCal_Hydronics Member Posts: 9
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    The electric TurboMax Hot Rod Suggested looks like a winner.

    Now, lets see if I can get one and how much they are.

    I am avoiding Heat Pumps because 1) I don't have cooling loads, so it is a bit of a waste. 2) Expensive 3) Heat pump water heaters are largely electric water heaters with a bit of heat pump thrown in.

    ethicalpaul
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,897
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    I am avoiding Heat Pumps because 1) I don't have cooling loads, so it is a bit of a waste. 2) Expensive 3) Heat pump water heaters are largely electric water heaters with a bit of heat pump thrown in.


    They are certainly expensive, but air-to-water heat pumps are not largely electric water heaters with a bit of heat pump thrown in.
    . They're like 3x more efficient!
    ethicalpaulSolid_Fuel_Man
  • Jamie Hall
    Jamie Hall Member Posts: 23,524
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    Um... I'd have to differ, but it's your call. A heat pump, in your climate, will use a third of the electricity for a given heating load than a straight electric boiler would. In California, I'd worry about that. A lot. The additional cost for the changeover valve in a heat pump system is small, as is the complexity. On the heat pump water heaters, most -- if not all -- of the better ones can be configured in the control menus so that they never use the resistance boost heaters, so again you are using a third or less of the electricity.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SoCal_Hydronics
    SoCal_Hydronics Member Posts: 9
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    Whose heat pump water heater model do you like? The existing system already has a Taco XPB handling radiant -- so if I can get a 40,000 BTU continuous out of the water heater -- that works too. I have been buying Spacepak AW heat pumps and they would still need a tank -- it makes them very expensive
  • pecmsg
    pecmsg Member Posts: 4,909
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    Greetings,

    I am sure I am not alone in being asked, quite often now, to provide all electric heating + DHW systems. Our region has natural gas infrastructure and NG is MUCH less expensive per KW than electricity. Even after carefully explaining the advantages of modern gas modcon boilers to highly educated individuals, they still express the desire to go electric. Science doesn't seem to have much to do with their decision -making. This seems to be a trend the last couple years... given the folks I see driving around masked in their cars, as well as biking, skateboarding -- you get the picture. This is California after all.

    Anyway -- Viessmann has introduced a new electric boiler line. The largest output model draws about 70 AMPS and produces 49MBH. I have a job where my radiant heat loss is about 40 MBH (so far so good) and I would also like to provide DHW via an indirect. 49MBH and an 80 gl tank would probably provide enough recovery for the 2 bath residence, but the boiler has a 140° output limit. This is a bit limiting to heat up a tank. Also, the boiler does not have separate HHW and DHW TT terminals and corresponding output temps -- so I would have to work around that.

    I am interesting in hearing from other professional as to how they would go about providing all electric HHW + DHW in this scenario.

    Thanks!

    For Hot water A Heat Pump water heater.
    EdTheHeaterMan
  • SoCal_Hydronics
    SoCal_Hydronics Member Posts: 9
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    Quick math tells me I can only get about 25MBH out of Heat Pump Water Heater for continuous use. That doesn't quite get it
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,153
    edited January 2023
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    Off Topic but to the point.
    In the 1990s the Cell phone companies were giving away Bag Phones to get people to use cell phone service. (which was expensive). I was smart and elected to save $1700.00 in the cost of Motorola two way radios for my 5 service trucks. Free equipment v. $1700.00 in Radio Equipment. No brainer. Go with the free stuff!

    18 months later after calculating that I spent over $2500 in cell phone air time, I purchased the Motorola Radio equipment for my service fleet. Unlimited air time.

    Today, you get unlimited air time on cell phones. But my bag phones are nowhere to be found. LOL

    So how expensive is an air to water heat pump in California today? And what do you expect to pay for electricity in the next 20 years (expected equipment life?)

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • pecmsg
    pecmsg Member Posts: 4,909
    Options

    Off Topic but to the point.
    In the 1990s the Cell phone companies were giving away Bag Phones to get people to use cell phone service. (which was expensive). I was smart and elected to save $1700.00 in the cost of Motorola two way radios for my 5 service trucks. Free equipment v. $1700.00 in Radio Equipment. No brainer. Go with the free stuff!

    18 months later after calculating that I spent over $2500 in cell phone air time, I purchased the Motorola Radio equipment for my service fleet. Unlimited air time.

    Today, you get unlimited air time on cell phones. But my bag phones are nowhere to be found. LOL

    So how expensive is an air to water heat pump in California today? And what do you expect to pay for electricity in the next 20 years (expected equipment life?)

    10 - 12 years is more realistic! And dont forget the repairs
  • Alan (California Radiant) Forbes
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    Back to your first conversation about electric boilers, I've had the same interest from my customers here in the Bay Area, but have yet to install one as I usually talk them out of it. Not that I don't like the idea, but it only makes sense if they have solar and if they do have solar, the electric boiler will usually use all and most likely more of what they generate.

    And adding a 70 amp load will often mean a service upgrade.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,352
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    Hi @SoCal_Hydronics , I too am in California. My understanding of it is that the state wants to be completely off of gas by 2030. So, imagine in the year 2031, you're selling your home. If it's on gas, that's going to be seen as a big, expensive negative. So, your clients that want to go all electric sound smart to me because they are looking to convert sooner and get the benefit of the various credits available now.

    Thinking in a systems sort of way, I'd do what I could to see where the energy is going and plug those leaks as best as possible. A really good house shell can save around 80% of the heating/cooling energy.

    More to your question, solar thermal and heat pump likely can provide enough heat as long as the emitters are designed and sized for working at low temperatures, in the range of 80F to 120F.

    Yours, Larry
  • hot_rod
    hot_rod Member Posts: 22,327
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    Quick math tells me I can only get about 25MBH out of Heat Pump Water Heater for continuous use. That doesn't quite get it

    Two thinks I learned trying to use a hpwh for my shop slab. About 1-1/2 ton capacity, maybe 18,000 btu/ hr
    And it discharged 47 degree air into the space. The heat has to come from somewhere for indoor air to water heat pump water heaters to work
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Zman
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,333
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    @SoCal_Hydronics, I've merged your two posts into one here to prevent confusion. Thanks!

    President
    HeatingHelp.com

    EdTheHeaterMan
  • ethicalpaul
    ethicalpaul Member Posts: 5,757
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    Whose heat pump water heater model do you like? The existing system already has a Taco XPB handling radiant -- so if I can get a 40,000 BTU continuous out of the water heater -- that works too. I have been buying Spacepak AW heat pumps and they would still need a tank -- it makes them very expensive

    My Rheem is ridiculously cheap to run, quiet and capable, and it runs exclusively in heat pump mode, with ZERO resistive heating.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    JakeCK
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,074
    edited January 2023
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    I’m waiting to see what Viessmann has to offer if and when their heat pumps are approved here.
     
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • JakeCK
    JakeCK Member Posts: 1,401
    Options
    I have a hpwh too and it has worked flawlessly for a year now. 

    It costs less to run that then my old gas water heater, and because of synergies with other equipment in the house my electric usage has not noticably increased since switching over to it. 

    Personally I feel anyone who doesn't give them serious consideration is doing a disservice to themselves or their customers. 
  • hot_rod
    hot_rod Member Posts: 22,327
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    If this is in Sol Cal your DHW load is maybe larger then the heat load. So hp for DHW, small electric boiler. PV with the savings🥴
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JakeCK
    JakeCK Member Posts: 1,401
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    hot_rod said:
    If this is in Sol Cal your DHW load is maybe larger then the heat load. So hp for DHW, small electric boiler. PV with the savings🥴

    Adding to what @hot_rod said, I'd imagine there are more cooling days then heating days in socal. That makes a hpwh an even sweeter deal since it is free cooling for the majority of the year.

    I wonder if it would allow a downsizing of the cooling required...
  • GroundUp
    GroundUp Member Posts: 1,934
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    Just to clarify, Viessmann bought NegtGen and put their name on NextGen electric "boilers" aka water heaters. They were a piece of crap when they said NextGen on them, and that has not changed with the new badge.

    I do a ton of electric boilers in my area as NG is not an option and electric is often much cheaper per BTU than LP. I have done a couple Electro boilers paired with indirects, but frankly, a regular old electric water and separate Electro boiler is the simplest and most cost effective in most cases.
  • hot_rod
    hot_rod Member Posts: 22,327
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    JakeCK said:


    hot_rod said:

    If this is in Sol Cal your DHW load is maybe larger then the heat load. So hp for DHW, small electric boiler. PV with the savings🥴

    Adding to what @hot_rod said, I'd imagine there are more cooling days then heating days in socal. That makes a hpwh an even sweeter deal since it is free cooling for the majority of the year.

    I wonder if it would allow a downsizing of the cooling required...
    Might be some attractive rebates for hpwh also.

    Www.dsireusa.org for state by state incentives
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream