different method of heating, does it feel really different?????

Love the Heat · Feb 7, 2015

Hi All...

We all know that 71F is 71F. This being said walking in a home heating at 71F with wood
feels very different than a 71F with a Heat pump.

The method I'm interested to know as how it feels is the one where I would heat water and have
a water to air exchanger in my existing plenum....How does it feel?????

Regards..

Floydian · Feb 7, 2015

Hello,

Nope, it won't feel any different using a water to air HX. Unless of course you turn the thermostat up

Forced air relies on convective heat transfer, not the most comfortable or efficient...wood stoves heat the air via convection as well but the big comfort advantage is the wood stove transfers most of its heat via radiant, which heats the objects not air. This is why everyone loves the feel of radiant heat. When all the surfaces around you are warmer, you will simply be warmer.

Comfort is all about the MRT( mean radiant temperature). Search that if you want the in depth, scientific explanation. HealthyHeating has the best info.

Hope that helps,

Noah

Eric Johnson · Feb 7, 2015

Wood heat always feels warmer to me. Most of it is probably psychological, but with hydronic and stove-radiant heat, the heat is always "on" which I think makes a difference.

Bob Rohr · Feb 7, 2015

Some will say Hydro-air heats and feels differently as their is no flame scorching a tin heat exchanger, like a forced air furnace.

With a properly sized hydronic coil you can run low water temperatures. Assuming the ducting can carry the heat to the remote registers efficiently.

Duct sealing and insulating is a nice upgrade when installing a hot water coil. Get as much of the heat energy to the room, this allows lowest operating supply temperature.

With hot water you can also do some fine tuning with ODR outdoor reset, and modulate water temperatures to some degree. Tie this into a variable speed blower and you can ramp down fan speed, and water temperature to help eliminate some short cycling on milder days.

Varying blower speed also eliminates the draft you feel every time a blower kicks on a full speed, some of the new air handlers rarely shut down, they just modulate all heating season. Nice for air quality control and adding humidity if needed. Humidity affects some people more than temperature. Same with nice wood floors and wood furniture

Plus you might be able to run some chilled water to do summer conditioning, and humidity removal.

hartkem · Feb 7, 2015

I have a water to air heat exchanger in my plenum heated by my wood boiler and it feels almost exactly the same as the regular furnace. Only difference I notice is the furnace lowers the humidity in the house more than the WAHX. Go radiant if you can

arbutus · Feb 7, 2015

Mean radiant temperature makes all the difference.

The floor in this house isn't warm ... until the outside air temperature gets to negative 10F or so.
At the same time, it is never cold.
The thermometer hanging on the wall reads 68 to 70 all the time, and it feels right toasty.

jrod770 · Feb 7, 2015

Bob Rohr said:
Some will say Hydro-air heats and feels differently as their is no flame scorching a tin heat exchanger, like a forced air furnace.

With a properly sized hydronic coil you can run low water temperatures. Assuming the ducting can carry the heat to the remote registers efficiently.

Duct sealing and insulating is a nice upgrade when installing a hot water coil. Get as much of the heat energy to the room, this allows lowest operating supply temperature.

With hot water you can also do some fine tuning with ODR outdoor reset, and modulate water temperatures to some degree. Tie this into a variable speed blower and you can ramp down fan speed, and water temperature to help eliminate some short cycling on milder days.

Varying blower speed also eliminates the draft you feel every time a blower kicks on a full speed, some of the new air handlers rarely shut down, they just modulate all heating season. Nice for air quality control and adding humidity if needed. Humidity affects some people more than temperature. Same with nice wood floors and wood furniture

Plus you might be able to run some chilled water to do summer conditioning, and humidity removal.

How does one properly size a hydronic coil for a water to air heat exchanger? I have a 75,000 BTU propane furnace with a 20 x 20 plenum on top. How do I size a heat exchanger for it, just by size of the plenum alone?

Fred61 · Feb 7, 2015

arbutus said:
Mean radiant temperature makes all the difference.

The floor in this house isn't warm ... until the outside air temperature gets to negative 10F or so.
At the same time, it is never cold.
The thermometer hanging on the wall reads 68 to 70 all the time, and it feels right toasty.

This applies to me also. Those could be my words. My experience exactly. One exception; My temperature never goes below 69F.

Love the Heat · Feb 7, 2015

jrod770 said:
How does one properly size a hydronic coil for a water to air heat exchanger? I have a 75,000 BTU propane furnace with a 20 x 20 plenum on top. How do I size a heat exchanger for it, just by size of the plenum alone?

I couldn't agree more , I have the same questionning, proper size for my LP system is 80KBtu, what size or BTU should I get if I get the water to air heat exchanger?????

Bob Rohr · Feb 7, 2015

Love the Heat said:
I couldn't agree more , I have the same questionning, proper size for my LP system is 80KBtu, what size or BTU should I get if I get the water to air heat exchanger?????

The best way to get the appropriate coil is to contact a coil dealer or manufacturers rep. Some of the brands have online sizing software.
\ First Company, Magic Air are a couple common names. They will need to know the water supply temperature, and GPM flow rate you have available. BTU load for the building, CFM, type of installation, up flow or down flow and where the coil will be added into the system, does it have an AC coil currently, what about a filter rack?

Does the furnace do an adequate job now, all rooms maintain temperature? Some times if the ducting was not sized properly additional return air or vents need to be included so you can move enough air.

Adding a coil adds static or flow resistance, sometimes the blower speed needs to be increased. Most newer furnaces have multi-speed fan motors, older versions had adjustable pulleys to increase speed.

Don't be tempted to buy a coil that just matches the plenum size, it really should be engineered and sized for you exact application to get best results.

heaterman · Feb 7, 2015

Love the Heat said:
Hi All...

We all know that 71F is 71F. This being said walking in a home heating at 71F with wood
feels very different than a 71F with a Heat pump.

The method I'm interested to know as how it feels is the one where I would heat water and have
a water to air exchanger in my existing plenum....How does it feel?????

Regards..

Pretty much the same as your regular furnace. I think some people perceive a small difference sue to the fact that i you keep the coil hot all the time there is always a little heat via convective air flow in the duct system.

But I'm assuming you're wondering because you have heard people talk about "hot water heat" or "radiant heat". Even those two types are completely different.
A true radiant system does not keep you warm by heating air. It keeps you warm by eliminating heat loss from your body by warming everything else in the rooms including walls and even window panes. This is the MRT or mean radiant temperature that a couple other guys were talking about up above.
The difference in a 70* room heated with forced air vs 70* via a true radiant system has to be experienced to be fully appreciated.

Love the Heat · Feb 8, 2015

Bob Rohr said:
The best way to get the appropriate coil is to contact a coil dealer or manufacturers rep. Some of the brands have online sizing software.
\ First Company, Magic Air are a couple common names. They will need to know the water supply temperature, and GPM flow rate you have available. BTU load for the building, CFM, type of installation, up flow or down flow and where the coil will be added into the system, does it have an AC coil currently, what about a filter rack?

Does the furnace do an adequate job now, all rooms maintain temperature? Some times if the ducting was not sized properly additional return air or vents need to be included so you can move enough air.

Adding a coil adds static or flow resistance, sometimes the blower speed needs to be increased. Most newer furnaces have multi-speed fan motors, older versions had adjustable pulleys to increase speed.

Don't be tempted to buy a coil that just matches the plenum size, it really should be engineered and sized for you exact application to get best results.

Thx for the excellent advice.....

heaterman · Feb 8, 2015

Basic advice along with what Hot Rod said above.....if you can oversize your coil it will allow you to provide adequate heat with lower water temps.
Many manufacturers rate their coils with 180* or even 200* water temps so pay attention to that. If you can run with 140 or even 130 * water you effectively double the heating capacity of your storage compared to a coil that provides just enough heat at 180*. Systems that need high water temps are hamstrung right off the bat..

Love the Heat · Feb 8, 2015

heaterman said:
Basic advice along with what Hot Rod said above.....if you can oversize your coil it will allow you to provide adequate heat with lower water temps.
Many manufacturers rate their coils with 180* or even 200* water temps so pay attention to that. If you can run with 140 or even 130 * water you effectively double the heating capacity of your storage compared to a coil that provides just enough heat at 180*. Systems that need high water temps are hamstrung right off the bat..

Hummm. so this is like right now I have an 80KBtu furnace and to come close to an equivalent I would put a 125KBtu coils rated at 180 deg. because my application would deliver let say 150 Deg..
Am i in the ball park?????
Regards

ihookem · Feb 8, 2015

I don't know if you are in the ballpark. One poster said over size the HX. I have an 80k btu furnace, so I bought an EKO 25 that is rated for 85K. So, I put in an 80K HX. I thought it made sense. The problem is, The EKO 25 does not keep up cause the HX lowers the water temps very quick without storage. I can have 180* water temps, run the boiler wide open and go from 180* to 140* in 1/2 hour. Then, my NG furnace kicks in so I lower the thermostat in the house to get the water back up to 180. By then the house has cooled off to what is was when I got home . By the time the wife is warm it was time for bed. I should have gotten a 40k HX so my boiler could at least keep up without lowering the water temps. It would have kept the water temps higher, put out hotter more comfortable air too. To fix the problem I stapled up 1000 ft of 1/2" pex in the kitchen, family room and some in the master bath to keep the tile a bit warmer. The house has a totally different feel. I have a strange hydronic set up. I have no thermostats. I run my 1/2" pex off the 1" copper pipe going to the HX. with 3 different ( zones) I control the temps in the house by adjusting the water temps on the boiler. If it is going to be a warm sunny day I put the boiler at 160. A cold day 165* keeps the house 68* @ 3' high. The floor however is about 75* It's a very comfy house. I hope this makes sense but I feel many are scratching their heads.

brant2000 · Feb 9, 2015

ihookem said:
I don't know if you are in the ballpark. One poster said over size the HX. I have an 80k btu furnace, so I bought an EKO 25 that is rated for 85K. So, I put in an 80K HX. I thought it made sense. The problem is, The EKO 25 does not keep up cause the HX lowers the water temps very quick without storage. I can have 180* water temps, run the boiler wide open and go from 180* to 140* in 1/2 hour.

This is very true and really should be taken into consideration when selecting/designing a system. The rated output for a furnace is (should be) always much larger than the actual max load. This allows it to cycle on and off in order to satisfy the heat demand. As noted, your EKO 25 cannot realistically keep up with an 80 MBH load on it, so the water temp starts to drop off. The best way to accommodate this is to provide enough storage/buffer to supply enough heat until the house temperature can be satisfied again. Once the furnace blower shuts off, the boiler can then start recharging that storage/buffer. Unfortunately, if you fall behind on the storage or don't have enough of it, you'll be playing a long game of catch up during a cold spell.

maple1 · Feb 9, 2015

Couldn't that be alleviated by slowing the circulation blower down? It would seem to be the size of the heatload (what the house needs for heat) vs the size of the HX. A bigger HX just shouldn't need the air moving across it as much or for as long to meet the house demand. I would think using a smaller HX would just result in the blower running for longer & not really reduce the amount of heat needed from the boiler, overall.

Love the Heat · Feb 9, 2015

ihookem said:
I don't know if you are in the ballpark. One poster said over size the HX. I have an 80k btu furnace, so I bought an EKO 25 that is rated for 85K. So, I put in an 80K HX. I thought it made sense. The problem is, The EKO 25 does not keep up cause the HX lowers the water temps very quick without storage. I can have 180* water temps, run the boiler wide open and go from 180* to 140* in 1/2 hour. Then, my NG furnace kicks in so I lower the thermostat in the house to get the water back up to 180. By then the house has cooled off to what is was when I got home . By the time the wife is warm it was time for bed. I should have gotten a 40k HX so my boiler could at least keep up without lowering the water temps. It would have kept the water temps higher, put out hotter more comfortable air too. To fix the problem I stapled up 1000 ft of 1/2" pex in the kitchen, family room and some in the master bath to keep the tile a bit warmer. The house has a totally different feel. I have a strange hydronic set up. I have no thermostats. I run my 1/2" pex off the 1" copper pipe going to the HX. with 3 different ( zones) I control the temps in the house by adjusting the water temps on the boiler. If it is going to be a warm sunny day I put the boiler at 160. A cold day 165* keeps the house 68* @ 3' high. The floor however is about 75* It's a very comfy house. I hope this makes sense but I feel many are scratching their heads.

In my limited knowledge... you have added storage by adding all of that 1/2" pex that you did not have in your HX...

heaterman · Feb 9, 2015

ihookem said:
I don't know if you are in the ballpark. One poster said over size the HX. I have an 80k btu furnace, so I bought an EKO 25 that is rated for 85K. So, I put in an 80K HX. I thought it made sense. The problem is, The EKO 25 does not keep up cause the HX lowers the water temps very quick without storage. I can have 180* water temps, run the boiler wide open and go from 180* to 140* in 1/2 hour. Then, my NG furnace kicks in so I lower the thermostat in the house to get the water back up to 180. By then the house has cooled off to what is was when I got home . By the time the wife is warm it was time for bed. I should have gotten a 40k HX so my boiler could at least keep up without lowering the water temps. It would have kept the water temps higher, put out hotter more comfortable air too. To fix the problem I stapled up 1000 ft of 1/2" pex in the kitchen, family room and some in the master bath to keep the tile a bit warmer. The house has a totally different feel. I have a strange hydronic set up. I have no thermostats. I run my 1/2" pex off the 1" copper pipe going to the HX. with 3 different ( zones) I control the temps in the house by adjusting the water temps on the boiler. If it is going to be a warm sunny day I put the boiler at 160. A cold day 165* keeps the house 68* @ 3' high. The floor however is about 75* It's a very comfy house. I hope this makes sense but I feel many are scratching their heads.

This^^^^^^

Very clearly illustrates the requirement of storage for any boiler based wood burning system.

Even if Hookem had a 40 or 60 EKO he would still have the lag time to deal with which would leave him with lukewarm air being circulated through his house while the boiler went from idle/off to full fire.
He has partially solved his problem by creating a little constant demand from his system which in turn keeps the boiler "on".

heaterman · Feb 9, 2015

Love the Heat said:
Hummm. so this is like right now I have an 80KBtu furnace and to come close to an equivalent I would put a 125KBtu coils rated at 180 deg. because my application would deliver let say 150 Deg..
Am i in the ball park?????
Regards

Yep you're getting it. The coil manufacturer should be able to get you specs on output @ given water temp/gpm flow.
If you do not have thermal storage you are going to have a much higher than desired number of on/off cycles regardless of the coil size. Not the best way for efficiency.

brant2000 · Feb 9, 2015

heaterman said:
Yep you're getting it. The coil manufacturer should be able to get you specs on output @ given water temp/gpm flow.
If you do not have thermal storage you are going to have a much higher than desired number of on/off cycles regardless of the coil size. Not the best way for efficiency.

A larger coil (ie, more tube rows and/or fins per inch) will transfer more heat with lower temperatures, but this still won't really address the problem. You'll still continue to drop your average system temp (even faster) since your heat input can't keep up with the heat output.

maple1 · Feb 9, 2015

But that also depends on air movement through it too - right?

heaterman · Feb 9, 2015

All the factors enter into the equation.
Coil surface area.
Type of coil (2 row, 3 row etc.)
GPM
CFM

BTU Heat transfer with air based system is CFM x 1.08 x ::DT

T

different method of heating, does it feel really different?????

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