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cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to Mr Matt

Re: Anyone have a suggestion for standby whole home generator?

said by Mr Matt:

I wonder if a tankless water heater would be able to supply sufficient heat.

Something like this should have no issue: »www.lowes.com/pd_364960-35419-J-···_price|0

pandora
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reply to cowboyro
said by cowboyro:

said by pandora:

The likelihood the strips will be used for any length of time is near zero.

Actually the likelihood is 100%.
Defrost cycles occur whenever the heat pumps detect a loss in performance due to icing. That means even above-freezing temperatures with enough humidity. If they don't defrost they will try defrosting over and over and your system will blow cold air. If I'm not too busy I'll post some hard numbers from my system later...

The DLM will prohibit them from running. Thus while they may be called, they will never get energized if my home is using a 20KW emergency generator.
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pandora
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reply to cowboyro
said by cowboyro:

said by pandora:

I shall see what happens and report back. If eating of crow is necessary, then I shall dine upon it, while investigating a propane furnace.

A propane-fired tankless heater + hydrocoils probably costs less than the difference between a big-ass generator and a smaller one that has no issue running on emergency heat.

I had auxiliary heat from hot water. I won't be running anti-freeze filled lines to my attic again. I've been there and done that.

Thanks for the though though.
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"People demand freedom of speech as a compensation for the freedom of thought which they seldom use."

pandora
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reply to Mr Matt
said by Mr Matt:

I found this website that offers an assortment of hydrocoils:

»www.altheatsupply.com/shop-by-ne···ers.html

I wonder if a tankless water heater would be able to supply sufficient heat. My Brother In Law used a quick recovery storage type water heater with a 75,000 BTU burner like this one:

»www.lowes.com/pd_89263-135-G2F75···cetInfo=

It heated a home office in his attic and provided hot water to a collocated bathroom. His costs were different because he used natural gas for heat.

I appreciate your help, but my mind is made up for the moment. If the system doesn't work, I'll write back and explain the failure. Time will tell.
--
"People demand freedom of speech as a compensation for the freedom of thought which they seldom use."
Expand your moderator at work

ncbill
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join:2007-01-23
Winston Salem, NC
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reply to pandora

Re: Anyone have a suggestion for standby whole home generator?

Have the new heat pumps been installed?

If not, why not ask your HVAC contractor for a modified quote on at least one unit?

It doesn't have to be anything fancy, but it would be easier on any genny to off-source the heating load to a furnace.

It sure is nice to have A/C, but I'm guessing in your climate having heat probably a little more important than having A/C.

I agree with you about the tankless/coil - and am very thankful for my basic, does-not-need-electricity water heater which burns cheap natural gas.


nunya
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reply to pandora

The DLM will prohibit them from running. Thus while they may be called, they will never get energized if my home is using a 20KW emergency generator.


The thing I don't think you are grasping is the heat strips HAVE TO RUN in order for the heatpump to work. They aren't optional. If you don't run them the heatpump will freeze and stop working. You can't have HP without the strips.

BTW, it doesn't have to be below freezing for your heatpump to freeze up. I've had mine ice over in the 40's with high humidity.
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Jack_in_VA
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said by nunya:


The DLM will prohibit them from running. Thus while they may be called, they will never get energized if my home is using a 20KW emergency generator.


The thing I don't think you are grasping is the heat strips HAVE TO RUN in order for the heatpump to work. They aren't optional. If you don't run them the heatpump will freeze and stop working. You can't have HP without the strips.

BTW, it doesn't have to be below freezing for your heatpump to freeze up. I've had mine ice over in the 40's with high humidity.

The heatpump will work fine with the strips off and not working. The condensing unit will go into defrost shutting the fan off and reversing the operation into air conditioner mode. Meanwhile inside the cold air from the registers will start to lower the inside temperature. Brrrrrrr. Been there done that when service tech forgot to turn breaker on for strips after routine semi-annual service in the fall.

pandora
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reply to ncbill
said by ncbill:

I agree with you about the tankless/coil - and am very thankful for my basic, does-not-need-electricity water heater which burns cheap natural gas.

My new electric hot water heater is a Geospring. Not certain how expensive it'll be to keep.

Three of the happiest days in my life recently was the day my oil furnace and related hot water heater were removed, the day my chimney was removed, and the day the two 330 gallon oil tanks were removed.

I'm off oil, and am happy. My electric rates are much more predictable. The 2nd generation Geospring seems to run well. Supposedly it costs about half as much as a conventional electric hot water heater. My understanding will improve better over time.

My last go at oil heat was a System 2000, which had to be repaired about 5 times over an 8 year period.

Our heat pump has worked well in winter and summer.

We shall see what happens. I understand many are better informed than I can be, and are probably much smarter. For better or worse, in my home, at least immediately after this renovation, it'll be heat pump, electric auxiliary heat and a Geospring (second generation) providing hot water.

I don't want to worry about oil tank level, or how much oil will cost for the next 400 gallon fill.
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pandora
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reply to nunya
said by nunya:


The DLM will prohibit them from running. Thus while they may be called, they will never get energized if my home is using a 20KW emergency generator.


The thing I don't think you are grasping is the heat strips HAVE TO RUN in order for the heatpump to work. They aren't optional. If you don't run them the heatpump will freeze and stop working. You can't have HP without the strips.

BTW, it doesn't have to be below freezing for your heatpump to freeze up. I've had mine ice over in the 40's with high humidity.

Never happened to my old unit. Don't know where or how that picture was taken, but my 7 year old Ruud never had anything approaching that on it.
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nunya
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That's because your heat strips are working!!!!!! Some HVAC guy please help me out here. I don't know how else to explain this any clearer.
I'll try one more time:
No heat strips = no heatpump. They aren't optional. You can't just turn them off and tell your HP to just ignore the laws of physics until commercial power comes back on.
It's an integral part of the system.
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shdesigns
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IT will work with the heat strips off.

The heat strips are usually after the coils. In defrost mode, they keep from blowing cold air during defrost:




You don't want them before the coils as it may cause a high head pressure.

Description and image from here: »www.geo4va.vt.edu/A3/A3.htm
--
Scott Henion

Embedded Systems Consultant,
SHDesigns home - DIY Welder

pandora
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reply to nunya
said by nunya:

That's because your heat strips are working!!!!!! Some HVAC guy please help me out here. I don't know how else to explain this any clearer.
I'll try one more time:
No heat strips = no heatpump. They aren't optional. You can't just turn them off and tell your HP to just ignore the laws of physics until commercial power comes back on.
It's an integral part of the system.

I think you are confusing the auxiliary heat in the air handler with defrosting done in the compressor. The auxiliary heaters in discussion are for the air handler, not for the defrost mode of the compressor.
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Jack_in_VA
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North, VA
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reply to shdesigns
said by shdesigns:

IT will work with the heat strips off.

The heat strips are usually after the coils. In defrost mode, they keep from blowing cold air during defrost:

[att=1]

You don't want them before the coils as it may cause a high head pressure.

Description and image from here: »www.geo4va.vt.edu/A3/A3.htm

That's exactly what I posted here: »Re: Anyone have a suggestion for standby whole home generator?

In defrost the unit is in cooling mode and would freeze you inside without either auxiliary heat strips.


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to nunya
said by nunya:

I'll try one more time:
No heat strips = no heatpump. They aren't optional. You can't just turn them off and tell your HP to just ignore the laws of physics until commercial power comes back on.
It's an integral part of the system.

Actually it will work. The effect will be similar to having the AC blasting cold air in the winter for 3-4 minutes but if that's what the OP wants...
The coils inside end up at the temperature of the return regardless of the strips being on or off.


Jack_in_VA
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said by cowboyro:

Actually it will work. The effect will be similar to having the AC blasting cold air in the winter for 3-4 minutes but if that's what the OP wants...
The coils inside end up at the temperature of the return regardless of the strips being on or off.

The temperature of the evaporator coil will be what the cold temperature of the unit can produce less the temperature of the return air that acts as a tempering medium on the coil. This air is then warmed by the strip heaters.

laserfan

join:2005-01-14
Texas
reply to pandora
said by pandora:

I think you are confusing the auxiliary heat in the air handler with defrosting done in the compressor. The auxiliary heaters in discussion are for the air handler, not for the defrost mode of the compressor.

I think I agree with this!

To further clarify, there are no "heat strips" in the outside condensing unit, and the Defrost Cycle simply reverses the valve from heating-back-to-cooling, thereby causing warmth from the indoor unit to flow thru the outside condenser coils.

Further, at least in my experience, this occurs WITHOUT energizing the indoor heat strips (10KW in our units) and AFAICT this owes to the system knowing it's in defrost mode, i.e. otherwise the heat strips might come-on because the heating thermostat is not satisfied.

pandora please correct me if I'm wrong.


Jack_in_VA
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said by laserfan:

I think I agree with this!

To further clarify, there are no "heat strips" in the outside condensing unit, and the Defrost Cycle simply reverses the valve from heating-back-to-cooling, thereby causing warmth from the indoor unit to flow thru the outside condenser coils.

The defrost cycle also turns the condensing unit fan off allowing the heat removed from the inside to build up on the outside condensing coils melting any ice accumulation.

Further, at least in my experience, this occurs WITHOUT energizing the indoor heat strips (10KW in our units) and AFAICT this owes to the system knowing it's in defrost mode, i.e. otherwise the heat strips might come-on because the heating thermostat is not satisfied.

On all my units I've ever had the defrost cycle brings on at least one heat strip to prevent the inside air to be excessively cooled. I have 15 kw and 5 of it automatically comes on and if the thermostat drops it sequences the other 10 kw on to maintain the inside temperature. The unit will try to maintain the inside temperature regardless if the unit is in a defrost cycle.

pandora
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reply to laserfan
said by laserfan:

said by pandora:

I think you are confusing the auxiliary heat in the air handler with defrosting done in the compressor. The auxiliary heaters in discussion are for the air handler, not for the defrost mode of the compressor.

I think I agree with this!

To further clarify, there are no "heat strips" in the outside condensing unit, and the Defrost Cycle simply reverses the valve from heating-back-to-cooling, thereby causing warmth from the indoor unit to flow thru the outside condenser coils.

Further, at least in my experience, this occurs WITHOUT energizing the indoor heat strips (10KW in our units) and AFAICT this owes to the system knowing it's in defrost mode, i.e. otherwise the heat strips might come-on because the heating thermostat is not satisfied.

pandora please correct me if I'm wrong.

I spoke with the HVAC person this morning. The auxiliary heat strips do not defrost the outside unit. The air handler (the device that blows air inside the house) when in heat pump mode (in heat mode) on auxiliary heat, will not blow air until the internal electric heater reaches a preset temperature. He says usually it's 120F to 140F but it is settable on install.

I will have my air handler configured to not blow cold air if the resistive heating element doesn't reach 120F when auxiliary heat is being called. This will prevent any blowing of cold air inside the house.

I have asked him to check and see if 15KVA units are acceptable.

In defrost, the compressors use about 2.5-3KW in winter when switching from heat pump mode, this is similar to their power consumption when not defrosting.

The HVAC person also indicated the compressors are able to know when frosting is occurring, and are able to wait to defrost until AFTER a heat cycle (meaning after no heat has been called for at least 3 minutes).

At the time the defrost would start, the house would not normally need heating anyway.

In a severe cold situation, AND while on generator, this could be a problem. To the best of my understanding this would require a several hour power failure (or longer) at a time when the outside temperature was lower than 10F.

Lower than -10F has occurred to the best of my recollection 4 times in the past 35 years of my life in this area. I do not recall losing power during any of those periods, as the air was still. The period of -10F temperatures usually lasts less than a few hours, but I recall one time where for about 30 hours it was between -10F and -17F. That happened in February of 1994. It has never been that cold for that long since.

During a sustained cold period, where auxiliary heat may be necessary, I'll be using 40KVA to heat my home of resistive heat per hour. My estimate is the cost would be nearly $170 per day IF only auxiliary heat was working and we had power from the utility. That assumes the auxiliary heat would run 24 hours non-stop. Until an event occurs, I'll be unable to provide factual information, at the moment it's somewhat informed speculation.
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nunya
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reply to pandora
You guys might be able to "get away" without the strips in a Southern climate, but in a harsh winter climate it's a different ball game.
I'm not sure where "Outland" is, but the OP says he is in a place where the temperature can get below 20 degrees.

Scott, the heat strips or combustion chamber are always before the a-coil here. I've never ever seen them after. Almost everyone has updraft furnaces in their basement.
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treeman
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Mcgaheysville, VA
reply to Bob4
If his living space is 936 and the bill was 350, and yours is twice the size 2x936=1872 and your bill is 438, I sure as hell glad I,m not heating like you guys. Our place is 3450sqft, would have to quit eating

pandora
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reply to nunya
said by nunya:

You guys might be able to "get away" without the strips in a Southern climate, but in a harsh winter climate it's a different ball game.
I'm not sure where "Outland" is, but the OP says he is in a place where the temperature can get below 20 degrees.

Scott, the heat strips or combustion chamber are always before the a-coil here. I've never ever seen them after. Almost everyone has updraft furnaces in their basement.

Outland is Connecticut. Our current heat pump can push out sufficient heat to keep our home 75F at about 15F outside. It's a 7 year old Ruud SEER 14, not certain of it's heat pump number. The newer units are rated to produce heat down to -10F.

If my experience with the Ruud wasn't so positive, I'd be more concerned about many of the suggestions here. Maybe the newer units are very inferior and will not perform well at all. I can't tell until they are installed and it gets cold. I know from first hand experience that 40F or below and heat pump is a very outdated rule of thumb.

Assuming the rule moves over time, for me it has been between 15 and 20F on the old unit, and may be different on the newer units.
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laserfan

join:2005-01-14
Texas
reply to pandora
said by Jack_in_VA:

On all my units I've ever had the defrost cycle brings on at least one heat strip to prevent the inside air to be excessively cooled. I have 15 kw and 5 of it automatically comes on and if the thermostat drops it sequences the other 10 kw on to maintain the inside temperature. The unit will try to maintain the inside temperature regardless if the unit is in a defrost cycle.

How do you know "5 automatically then 10 if it has to"? You must have multistage heating then, huh (though I still wonder how you know "1st stage, 2nd stage" are on? I don't think even if my TH8000 were wired for 2-stage that there's an indication of it, and right now it only says EM HEAT when the strips are on).

said by pandora:

I spoke with the HVAC person this morning. The auxiliary heat strips do not defrost the outside unit. The air handler (the device that blows air inside the house) when in heat pump mode (in heat mode) on auxiliary heat, will not blow air until the internal electric heater reaches a preset temperature. He says usually it's 120F to 140F but it is settable on install...

I'm sure both of you guys know your setups, but I don't think any of this stuff is universally true. At least, I have 1-stage of Em Heat and Jack's is fancier, and I can't find any reference in my fan coil documentation to a sensor that turns on the fan only when the elements are warm. And I swear I've never seen at least an indication of Em Heat in the t-stat when a heat pump is in its defrost cycle.

All these questions though have inspired me to pay closer attention to my exact system operation when the next cold snap occurs in So Central Texas (hopefully not until late Dec or Jan!). Though I hope now to do a generator before that...hmmm.


cowboyro
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join:2000-10-11
Shelton, CT
reply to nunya
said by nunya:

You guys might be able to "get away" without the strips in a Southern climate, but in a harsh winter climate it's a different ball game.
I'm not sure where "Outland" is, but the OP says he is in a place where the temperature can get below 20 degrees.

My heat pumps (Trane) deliver good heat down to 10F. They have a built-in switch to auxiliary below 10F, but the cost of the heat delivered is still lower than producing equivalent heat on oil. The only reason for which a half-decent heat pump doesn't heat (besides being defective) is that it's undersized. Both power consumed and efficiency decrease with temperature, as a result the amount of heat being output is much lower while the heat losses in the house increase.
said by nunya:

Scott, the heat strips or combustion chamber are always before the a-coil here. I've never ever seen them after.

That makes no sense whatsoever. Auxiliary heat sources should be after the coils, not before. You want the final temperature of the "hot side" to be as low as possible, as the heat transfer efficiency decreases when the difference between hot and cold increases...

ncbill
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reply to pandora
Ummm...the first generation Geosprings have some pretty terrible reviews as to their performance & reliability.

E.g. poor recovery vs. conventional tank, interminable wait for parts (30+ days).

Note that these type of water heaters offer better performance in a hot climate like mine vs. a cold climate such as yours.

Be sure to buy the extended warranty - looking at online discussions you'll probably need it.

Was it your choice or suggested by your contractor?

said by pandora:

said by ncbill:

I agree with you about the tankless/coil - and am very thankful for my basic, does-not-need-electricity water heater which burns cheap natural gas.

My new electric hot water heater is a Geospring. Not certain how expensive it'll be to keep.


pandora
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said by ncbill:

Was it your choice or suggested by your contractor?

I have 10 years warranty from Lowes. My contractor only understands basic devices. The Geospring was his first.

Often when dealing with trades people, I feel like it's 1960. Many do not understand Internet, a number of electricians did not understand my desire for Cat 6 wiring, two suggested everyone uses wireless.

I tend to like new technology, the 2nd generation Geospring seems nice.
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