qcroanoke
Sometimes I don't know if I'm the boxer or the bag
- Location
- Roanoke, VA.
- Occupation
- Sorta retired........
Your easiest solution is probably an aquarium heater and control.
I would look at a Koi pond heater
Your easiest solution is probably an aquarium heater and control.
I've been there, power is out during cold weather, one doesn't even think of hot tub once power is out. Most outages are only a few hours at the most. it is when that unusual condition happens and it is say 10 days when that hot tub will get you. If it isn't too extremely cold it likely pulls through without freezing. By the third or fourth day I might think about the hot tub, it is then I will place something in the plumbing area to provide some heat - or maybe even drain the tub. The tub I have is a small one and just draining it does remove enough water from critical places you shouldn't need to worry about any residual water causing damage if it freezes though.
Um.....maybe no electric at all. open drain just slightly, run a hot water garden hose to fill just slightly.
Um.....
Where would you get the hot water if there was no power for a week?
OK. But city water isn't likely to be hot.1. City water
2. Gas-fired water heater, with a standing pilot.
OK. But city water isn't likely to be hot.
And a gas fired heater may have some electrical control.........
Actually, the very notion of a hot tub freezing is beyond my horizon.
i still have hot water without poco, gas fired heater and city water, always pressure and hot. obviously an issue if the home is not setup that way, etc.
Is there a way to keep a hot tub from freezing during a power outage utilizing a portable generator? I'm looking at powering a home with a 7.5KW portable during any power outages. It will all be done to code with an interlock, inlet, signage, inspection and all the rest. I have done several of these already.
Of course the HT needs a 50 to 60 amp circuit to fully function so the generator will not be large enough for that. I would expect it to be able to run just the pump and not the heat but i don't even know if that is an option on a hot tub. If not, are there other ways of keeping the thing from freezing. I'm picturing running a cord from a GFCI receptacle and plugging in some kind of submersible heater that might draw only a few amps.
He has city water and a gas water heater. If that gas WH has a standing pilot it needs no electric power. Ignition is via the standing pilot and combustion draft is via natural convection.City hot water?
New one on me.
Not a bad idea if you have large enough generator to run it with everything else off.How about if you ran the hot tub off the generator, but only for 15 minutes or so per day, while you pretty much shut off all the house loads?
It was right about new years day 2007 when we lost power for 10 days after an ice storm. I have a 8000 watt portable generator. If I would have fed gas to that thing for a month at that time would have amounted to about a $900 electric bill compared to the usual $150-200 bill from the electric company at that time of the year. It wasn't extremely cold -hot tub (which I didn't have one at that time) would have likely made it through those 10 days without freezing. Adding a 60 or 100 watt lamp inside the mechanical compartment definitely would have been enough heat to not worry about much. If outage were going to be reaching 30 days - I would have drained the thing, and we would have went to town and stayed with friends or relatives.make the gen bigger, leave tub alone at a min set temp
Yes, that's what I thought probably FZ meant butHe has city water and a gas water heater. If that gas WH has a standing pilot it needs no electric power. Ignition is via the standing pilot and combustion draft is via natural convection.
Hopefully we are shooting for only being able to deal with a week maybe two weeks without power - with unknown low temperatures. Major disaster and anticipated longer outage - maybe better just drain the tub if it is going to be cold enough to freeze up if you don't otherwise have sufficient standby power to allow it to run normally.Enough with the light-bulb jokes already. (or Appalachian Engineerin' proposals, whichever the case may be)
First, you need to make a few decisions: Is this to be autonomous, or will you require the homeowner(s) to take action outdoors during a winter blackout? Do you want to assure that it's protected from freezing, or is a halfway measure acceptable?
If it's to be autonomous, and upsizing the generator isn't an option, I recommend installing a strip heater under the hot tub, with a thermostat set for 40°F, on its own independent circuit which will be live during generator operation.
(and the main hot-tub circuit needs to be interlocked with the generator circuit)
If you want to assure that it's protected from freezing, you can't just guess at the amount of heat required. Calculate the surface area exposed to the weather (including the bottom) and the effectiveness of the insulation. ("R" value) That, and the temperature difference required (I suggest a ΔT of 40-50°F, depending on which part of Massachusetts it's in) will tell you how much heat is required.
Making a few rough estimates, I calculated that a few thousand BTU/hour (several hundred watts) are required for long-term protection, and that it will take a few days for the water temperature to drop to freezing. Several more days would be required for the tub to freeze solid, but you can't rely on that because the water in the pipes and pump body won't benefit from the thermal inertia of the ton of water in the tub.
(I'm being deliberately vague because I don't know any of the actual parameters)
Because the small water-filled spaces (pipes & pump bodies) will freeze within a day or two, the same preparations are required for riding out a two-day outage as for a week or a month.Hopefully we are shooting for only being able to deal with a week maybe two weeks without power - with unknown low temperatures. ...
I agree but conditionally. If the outage occurs in December, January or February (around here) that chance of being cold enough to be an issue increases. If the tub were up to normal operating temp when the outage starts and the outdoor temp stays above maybe 20 deg F, and the outage doesn't last for more then a couple days - probably not going to cause a problem.Because the small water-filled spaces (pipes & pump bodies) will freeze within a day or two, the same preparations are required for riding out a two-day outage as for a week or a month.
The low temperatures are far from unknown; they're published by ASHRAE*. Boston, for example, can expect temperatures at or above -14°C to occur 99% of the time, (all but 3.65 days out of the year) making that a reasonable temperature for designing heating equipment.
These data were published a while ago and do not take global climate change into account. Current and future winters (and summers) are likely to be more severe.
*American Society of Heating, Refrigeration & Air-Conditioning Engineers, www.ashrae.org
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correct.He has city water and a gas water heater. If that gas WH has a standing pilot it needs no electric power. Ignition is via the standing pilot and combustion draft is via natural convection.