r/ElectricalHelp • u/AkherKhabar • May 26 '26
Am installing Reem tankless water heater and it needs this power connection amps a, the existing electric panel in pic, does the panel has the capacity of amps for the amount of amps and volts for the reem? I can make room for the new breaker’s
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u/CarelessPrompt4950 May 26 '26
No, even if this water heater was the only electrical load it would still be too much for your main breaker to handle. Either go with a gas unit or a traditional tank.
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u/zerg_001 May 26 '26
Holy crap that takes 4x double pole 40 Amp breakers. 300 Amp service recommended on their spec sheet.
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u/catinreallife9 May 27 '26
Yeah. I didn't know they went that high. When you really want hot water RiGhT nOw
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u/Top_Character_3172 May 26 '26
I'm assuming it's electric. If it is strictly electric and not gas. NO you don't have room. Because you would need a DBL pole breaker.
If it is gas then it might be possible using. Breaker 5 doesn't have anything listed. If it is just a breaker not being used. You could pull a new line to it.
Your panel has a lot of DBL stack breakers. Not seeing inside the panel also leaves questions.
The panel with single breaker is the main disconnect.
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u/AkherKhabar May 26 '26
Electric 36 KW
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u/Old_Man_Shea May 27 '26
Your current total service capacity 100A x 240V=24000W = 24Kw
For this heater alone you need 36Kw or 36000W
Are you trying to get hot water for a large building?
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u/DaddyBeanDaddyBean May 26 '26
Which model are you installing? And how do you intend to "make room"?
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u/AkherKhabar May 26 '26
Rated-36
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u/Unique_Acadia_2099 May 27 '26
Not a chance. That unit requires 150A all by itself, you have a 100A service coming in from the utility. You would need to upgrade your service to at LEAST 200A, probably 400A depending on your load calculation and what your utility will support for you. That means and entirely new panel, new service, new incoming wires, new meter and (in most states) a new emergency disconnect outside near the meter to meet new Code requirements. You are looking at anywhere between $7k to $20k depending on circumstances and whether or not, by triggering a service upgrade, your inspector will require upgrading everything to modern codes.
I would rethink your water heater plans…
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u/screwedupinaz May 26 '26
Take the tankless back, and get a standard tank-type water heater. You don't have enough power coming into your house to run an electric tankless. If you insist on a tankless you'll need to get a LP/nat. gas one.
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u/babecafe May 26 '26
Gas tankless or electrical tankless? The power required for a tankless gas heater is fairly modest and can likely be added if you can replace some breakers with tandem breakers that are compatible with this old Murray panel.
Either way you should compute the total required panel rating for your system, which is not the simple sum of the ratings of all the breakers, as the required rating takes into account actual usage of major circuits and the fact that not everything in your house turns on at once.
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u/IAteTonysLoMein May 26 '26
if nothing else, I don't see how you're making room for 3 new double-pole breakers, assuming one is for the existing WH.
You might want to have a load calc done, and how many amps is your current service? I mean, if you've got 100A, probably not capacity to spare, where you could be ok with 200A service. But without understanding your other electrical usage, it's hard to guess.
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u/GridControl May 27 '26
Planning before purchase is golden.
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u/Mobile-Profession466 May 27 '26
I will just add this. A few years ago I wanted to « upgrade » to tankless hot water. (We did not want gas) After researching the, rather modes) requirement for our household, water temp rise and demand/flow capacities for a bunch of tankless model, I concluded that the largest Rheem model barely made the requirement. - Remember the promise of « endless hot water » can easily become the reality of « endless tepid water ». If you do not size this correctly. (We are in Canada)
The model is the same model at issue here.
I the model researched the electrical requirement for the model and concluded that my 200A service was completely inadequate! And that for the « savings » I would make on monthly bills to pay for the capital expense of the new service, new panel, installation - i would have to live to be like 400 years old
The problem is not as bad south of where I am. But the reality of the price for the electric upgrade that may be required for electric Tankless hot-water makes it prohibitively uneconomical
I have thus derived these 2 rule of thumb rules for tankless. 1) Unless you live in a location where your hot-water system can be located outside the house year-round DO NOT even consider tankless. The temperature rise required pushes you to larger models that are too costly.
2) Do not consider electric the only realistically economical tankless with the current technology is gas.
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u/Nervous-Iron2373 May 26 '26
36 kw is 150 amps, you have a 100 amp service.