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bornontheblue

Radiant Floor heating Systems

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On 9/13/2022 at 11:47 AM, happycamper said:

usually you put them in slab on grade. it is expensive, it also works better. pita during framing instead of after framing. what I have seen done in some houses is drop the floor joist depth just at a bathroom to provide a depth difference, have radiant floor heating just in the bathroom, and make up the difference in the gyprete cover. 

It is undoubtably nicer than conventional heating. but it isn't usually enough nicer unless you are, say, Suzie McMurry or Cole Cercy. Examples given for no reason whatsoever.... :whistle:

Do you end up drilling a million holes in the joists? Doesn't that compromise the integrity of the joists?

 

Casper rich people? I'm not following

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On 9/13/2022 at 1:50 PM, Bob said:

Do you end up drilling a million holes in the joists? Doesn't that compromise the integrity of the joists?

No. Say you have 11 7/8" joists in most of the house. For the bathroom you'd use 9 1/2" joists, keeping the bottom of joist the same elevation. So now you have not quite 2 1/2" you can fill with gyprete, enough for some systems. 

On 9/13/2022 at 1:50 PM, Bob said:

 

Casper rich people? I'm not following

When I worked in Casper I did engineering for lots of stuff. load rating, oilfield stuff, restaurants.... big custom houses... lots of stuff :)

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On 9/13/2022 at 10:26 AM, happycamper said:

and I reiterate. that is not "extreme" enough for colorado (or minnesota) but it works fine for washington or idaho. you need a secondary system. a heating system that stops working right when you absolutely need heat to keep from dying and your pipes from bursting doesn't work when it reliably gets -20 and can be expected to get -30 to -40. you need a secondary system. 

Design temperature is -6 in Denver so these are definitely used there. Gas/electric backup where super important. Hasn’t gotten below -17 in Denver in over a decade. Adding a few supplementary electric heaters is still more cost effective than going with a gas-fired furnace.

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On 9/13/2022 at 2:36 PM, bsu_alum9 said:

Design temperature is -6 in Denver so these are definitely used there. Gas/electric backup where super important. Hasn’t gotten below -17 in Denver in over a decade. Adding a few supplementary electric heaters is still more cost effective than going with a gas-fired furnace.

damn, really? the 6 discontinuous years I lived in CO it got below -20 for about a week every year. 

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On 9/13/2022 at 12:40 PM, happycamper said:

damn, really? the 6 discontinuous years I lived in CO it got below -20 for about a week every year. 

Colorado is great because it can snow but it isn't bitter cold like a lot of the country.  If it gets into single digits, that is REALLY cold for Colorado(front range).  Here are the average temps:

https://www.denver.org/about-denver/resources/weather/

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On 9/13/2022 at 12:36 PM, bsu_alum9 said:

Design temperature is -6 in Denver so these are definitely used there. Gas/electric backup where super important. Hasn’t gotten below -17 in Denver in over a decade. Adding a few supplementary electric heaters is still more cost effective than going with a gas-fired furnace.

But your pipes aren't going to burst on the front range of CO without supplementary heat, correct?  You just may be more comfortable if you roll out a space heater as well if it gets really cold into the single digits and below.  

Plus, I think some of these mini split systems have a supplementary electric heater built in as well for those crazy cold days.  I am not sure how that works or if I am correct on that.

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On 9/13/2022 at 3:28 PM, Akkula said:

But your pipes aren't going to burst on the front range of CO without supplementary heat, correct?  You just may be more comfortable if you roll out a space heater as well if it gets really cold into the single digits and below.  

Plus, I think some of these mini split systems have a supplementary electric heater built in as well for those crazy cold days.  I am not sure how that works or if I am correct on that.

I mean yes they absolutely are, akkula. 

On 9/13/2022 at 3:25 PM, Akkula said:

Colorado is great because it can snow but it isn't bitter cold like a lot of the country.  If it gets into single digits, that is REALLY cold for Colorado(front range).  Here are the average temps:

https://www.denver.org/about-denver/resources/weather/

Did you ever live in Colorado, Akkula? You see negative temperatures along the front range every year. -20 was common annually in Fort Collins - like every 2nd week in February for several years running. For that matter, Colorado is, uh, arid and prone to extreme temperatures. You absolutely cannot just rely on a heat pump when you can reasonably expect it to get down to -25 or -30 every 20 years or so. 

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On 9/13/2022 at 1:40 PM, happycamper said:

I mean yes they absolutely are, akkula. 

Did you ever live in Colorado, Akkula? You see negative temperatures along the front range every year. -20 was common annually in Fort Collins - like every 2nd week in February for several years running. For that matter, Colorado is, uh, arid and prone to extreme temperatures. You absolutely cannot just rely on a heat pump when you can reasonably expect it to get down to -25 or -30 every 20 years or so. 

Dude,  I lived there for decades since birth... but you can just look at historical average monthly lows.  Overengineering a hvac system doesn't seem smart.   It could also sometimes reach 115 degrees but ac shouldn't be designed for that rare case. 

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On 9/13/2022 at 3:57 PM, Akkula said:

Dude,  I lived there for decades since birth. 

and just... forgot the weather? 

I mean they don't grow fruit trees on the front range for a reason lmao

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On 9/13/2022 at 12:40 PM, happycamper said:

Did you ever live in Colorado, Akkula? You see negative temperatures along the front range every year. -20 was common annually in Fort Collins - like every 2nd week in February for several years running. For that matter, Colorado is, uh, arid and prone to extreme temperatures. You absolutely cannot just rely on a heat pump when you can reasonably expect it to get down to -25 or -30 every 20 years or so. 

I agree with you and would absolutely want auxiliary heat anywhere where the temperatures drop that low, but energy codes and decarbonization are making it tough on builders and engineers.  Codes don't allow you to design around extremes either, you just go with 99%ile or 99.6%ile.  

I think with new refrigerants coming out operating conditions on some equipment will be able to handle just about any climate.  There are currently CO2 (as a refrigerant) heat pumps that can operate at -25F, and some VRF (fancy commercial grade heat pumps) can operate at -32F (but at like 50-70% capacity).  

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On 9/13/2022 at 12:28 PM, Akkula said:

Plus, I think some of these mini split systems have a supplementary electric heater built in as well for those crazy cold days.  I am not sure how that works or if I am correct on that.

They typically don't because  almost all the electric power is at the outdoor unit and you'd have to upsize the circuits/breakers.  For a typical 3-ton (36,000 btu/h) heat pump you only would use about 4 kW max.  If you wanted 36,000 btu/h from electric resistance heat only, you'd need over 10 kW.

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On 9/13/2022 at 2:00 PM, happycamper said:

and just... forgot the weather? 

I mean they don't grow fruit trees on the front range for a reason lmao

Dude... the absolute lowest temp in Denver 2021 was minus 16.  If you are telling me the average low is anywhere near that in the coldest months you are just being pig headed.   I gave you the numbers.  The average low in January is 16 degrees.   Well over zero. 

 https://www.google.com/amp/s/kdvr.com/weather/denver-records-lowest-temperature-of-the-year/amp/

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On 9/13/2022 at 4:02 PM, bsu_alum9 said:

I agree with you and would absolutely want auxiliary heat anywhere where the temperatures drop that low, but energy codes and decarbonization are making it tough on builders and engineers.  Codes don't allow you to design around extremes either, you just go with 99%ile or 99.6%ile.  

Wait, really? I would have said "are you shitting me" but I believe you. Man for structural engineering we work around the, hmm, roughly 99.9999th percentile (one failure per million item years - so if I design 50,000 houses, I would expect one failure in 20 years). The 99.6th percentile for something like heating... jfc. that is asking for a whole town to be devastated. 

On 9/13/2022 at 4:02 PM, bsu_alum9 said:

I think with new refrigerants coming out operating conditions on some equipment will be able to handle just about any climate.  There are currently CO2 (as a refrigerant) heat pumps that can operate at -25F, and some VRF (fancy commercial grade heat pumps) can operate at -32F (but at like 50-70% capacity).  

that would work pretty well then. 

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On 9/13/2022 at 4:06 PM, Akkula said:

Dude... the absolute lowest temp in Denver 2021 was minus 16.  If you are telling me the average low is anywhere near that in the coldest months you are just being pig headed.   I gave you the numbers.  The average low in January is 16 degrees.   Well over zero. 

 https://www.google.com/amp/s/kdvr.com/weather/denver-records-lowest-temperature-of-the-year/amp/

right. and about every 20 years, it dips and stays below -25. fort collins edges on -40 in its records and has multiple months below -30. 

if your heating system stops working at -10, and it gets -25 for a night, you're +++++ed. means lots of water damage, means some people freeze to death. it is nuts to say "let's just lose the ability to heat right when it becomes necessary to prevent death and structural damage". 

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On 9/13/2022 at 1:09 PM, happycamper said:

Wait, really? I would have said "are you shitting me" but I believe you. Man for structural engineering we work around the, hmm, roughly 99.9999th percentile (one failure per million item years - so if I design 50,000 houses, I would expect one failure in 20 years). The 99.6th percentile for something like heating... jfc. that is asking for a whole town to be devastated. 

For sure.  But historically failing to keep up with your design temperature doesn't actually mean failure.  It just means your house drops down to 65°F on the coldest day of the year.  But with heat pumps where they can completely lose heating?  Yikes.  

Most mechanical equipment is expected to fail in 20 years anyway, lol.  Especially newer high-efficiency furnaces and heat pumps. 

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On 9/13/2022 at 2:14 PM, happycamper said:

right. and about every 20 years, it dips and stays below -25. fort collins edges on -40 in its records and has multiple months below -30. 

if your heating system stops working at -10, and it gets -25 for a night, you're +++++ed. means lots of water damage, means some people freeze to death. it is nuts to say "let's just lose the ability to heat right when it becomes necessary to prevent death and structural damage". 

What?  You are going to assume that the heating system will experience 100% catastrophic failure if it drops below zero?  I would think the more likely scenario would be it wouldn't be able to consistently maintain 70 degrees and it may be cranked at 100% all the time and using a lot of energy.  

Like ...put on a sweater and get out the heavy blankets....not that you would be living in an ice palace suddenly....

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On 9/13/2022 at 1:18 PM, Akkula said:

What?  You are going to assume that the heating system will experience 100% catastrophic failure if it drops below zero?  I would think the more likely scenario would be it wouldn't be able to consistently maintain 70 degrees and it may be cranked at 100% all the time and using a lot of energy.  

Like ...put on a sweater and get out the heavy blankets....not that you would be living in an ice palace suddenly....

Electric and Gas heat, yes you are correct.

Heat pumps?  No, they just stop working at a certain temperature.

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On 9/13/2022 at 2:21 PM, bsu_alum9 said:

Electric and Gas heat, yes you are correct.

Heat pumps?  No, they just stop working at a certain temperature.

Good to know.  But what are those temperatures that would be recommended for a climate like the front range of Colorado?  It seems like the government is recommending them quite a bit.  I get the impression there is a lot of old school thinking here on this...

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On 9/13/2022 at 4:18 PM, bsu_alum9 said:

For sure.  But historically failing to keep up with your design temperature doesn't actually mean failure.  It just means your house drops down to 65°F on the coldest day of the year.  But with heat pumps where they can completely lose cooling?  Yikes.  

Most mechanical equipment is expected to fail in 20 years anyway, lol.  Especially newer high-efficiency furnaces and heat pumps. 

Yikes indeed. It felt fine in Wenatchee as it just... never gets cold there (extremes were very close to averages). In tennessee the winters are a lot warmer but the record lows are actually lower. But...we have an honest to god brick fireplace and more fallen wood than I know what to do with. so there's my backup system!

On 9/13/2022 at 4:18 PM, Akkula said:

What?  You are going to assume that the heating system will experience 100% catastrophic failure if it drops below zero?  I would think the more likely scenario would be it wouldn't be able to consistently maintain 70 degrees and it may be cranked at 100% all the time and using a lot of energy.  

Like ...put on a sweater and get out the heavy blankets....not that you would be living in an ice palace suddenly....

YES AKKULA THAT IS EXACTLY HOW HEAT PUMPS WORK. THEY STOP WORKING ONCE THE TEMPERATURE GOES BELOW A CERTAIN AMOUNT. IT ISN'T "IT DOESN'T PUT OUT ENOUGH HEAT ANY MORE TO STAY A COZY 72" IT IS "IT LOSES ~90% OF ITS EFFICIENCY AT 0 FOR MOST SYSTEMS AND JUST STOPS WORKING MUCH BELOW THAT. THAT IS A CATASTROPHIC FAILURE.

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On 9/13/2022 at 4:23 PM, Akkula said:

Good to know.  But what are those temperatures that would be recommended for a climate like the front range of Colorado?  It seems like the government is recommending them quite a bit.  I get the impression there is a lot of old school thinking here on this...

AKKULA JFC I'M 30 YEARS YOUNGER THAN YOU 

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