Ttystikk's vertical goodness

Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
Delta T is insufficient for a blow thru solution so flipping the blower around to draw through the core will make the difference, I'm sure of it.

You want to blow through cold water cores, not hot ones. This approach puts compression heating to work for you. Not applicable to water as it's incompressible.
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It depends on the coil design really but again it doesn't matter much that I'm aware of. Again most hot water airhandlers have the coil above the blower ;). What's compression heating?
 
Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
I snagged a bunch of radiators from 1980s Volvos from the local junkyard and built them into water cooled air handlers. Because there was no added manufacturing needed, just some fittings, I guarantee my solution was far more eco friendly than those!
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Way to go you Eco warrior :). I buy old stuff because I'm cheap lol. Perhaps due to design of the new stuff your energy usage would be less, now that you've used the old shit they need raw materials for the new shit ;). Just saying lol.
 
ttystikk

ttystikk

Well-Known Member
Budley Doright said:
It depends on the coil design really but again it doesn't matter much that I'm aware of. Again most hot water airhandlers have the coil above the blower ;). What's compression heating?
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Try this experiment if you don't think it makes a difference;

Hook up a vent fan to blow thru a hood and fire up a thouie in it. When the lamp gets hot, start the fan. Let it all run for an hour and take measurements or just use your hands. How hot is the hood?

Now flip the fan around so it sucks air through the hood. Leave the lamp running so nothing cools, then let it run for just 5 minutes and take more measurements.

You tell me which one runs cooler.
 
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Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
Try this experiment if you don't think it makes a difference;

Hook up a vent fan to blow thru a hood and fire up a thouie in it. When the lamp gets hot, start the fan. Let it all run for an hour and take measurements or just use your hands. How hot is the hood?

Now flip the fan around so it sticks air thru the hood. Leave the lamp running so nothing cools, then let it run for just 5 minutes and take more measurements.

You tell me which one runs cooler.
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No lol. All I'm saying is most if not all hot water airhandlers I have installed or seen have the coil on top, so I doubt it matters much not arguing sheeesh. I don't care where you put it lol. All im saying is I doubt it makes much difference but if you think so then cool (pardon the pun) change it.
 
ttystikk

ttystikk

Well-Known Member
Budley Doright said:
No lol. All I'm saying is most if not all hot water airhandlers I have installed or seen have the coil on top, so I doubt it matters much not arguing sheeesh. I don't care where you put it lol. All im saying is I doubt it makes much difference but if you think so then cool (pardon the pun) change it.
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The experiment I suggested will tell you that indeed it does make a substantial difference whether you pull or push air through a core. You want to push warm air through a cold coil to cool it more effectively and pull cool air through a hot core to heat it most efficiently. It isn't rocket science, is simple physics; in this case gas law.

The reason it 'doesn't seem to matter' is down to the temp if the water in the core; they want 160-180F, at 100 degrees is a big enough delta T that the inefficiency is masked. I'm running a delta T of only 25F, so it's a big difference.
 
Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
The experiment I suggested will tell you that indeed it does make a substantial difference whether you pull or push air through a core. You want to push warm air through a cold coil to cool it more effectively and pull cool air through a hot core to heat it most efficiently. It isn't rocket science, is simple physics; in this case gas law.

The reason it 'doesn't seem to matter' is down to the temp if the water in the core; they want 160-180F, at 100 degrees is a big enough delta T that the inefficiency is masked. I'm running a delta T of only 25F, so it's a big difference.
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Cool ;)
 
Budley Doright

Budley Doright

Well-Known Member
http://mobile.rheem.com/products/heating_and_cooling/air_handlers/
This is just one of the airhandlers that I'm used to working on but there pretty much all the same. You'll notice the cooling coil on most is pull through and the water coil is blow through. So my thoughts would be, can't be a huge difference but they may be doing it all wrong I guess. Most AC coils are on top of a (most popular) gas furnace but that has nothing to do with effeincy if perhaps that is what your thinking :).
 
Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
The experiment I suggested will tell you that indeed it does make a substantial difference whether you pull or push air through a core. You want to push warm air through a cold coil to cool it more effectively and pull cool air through a hot core to heat it most efficiently. It isn't rocket science, is simple physics; in this case gas law.

The reason it 'doesn't seem to matter' is down to the temp if the water in the core; they want 160-180F, at 100 degrees is a big enough delta T that the inefficiency is masked. I'm running a delta T of only 25F, so it's a big difference.
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No you don't want a delta t of 100 in a conventional boiler that is running 180, I would be installing replacement boilers every day lol. They would be giant piles of rust ;).
 
ttystikk

ttystikk

Well-Known Member
Budley Doright said:
No you don't want a delta t of 100 in a conventional boiler that is running 180, I would be installing replacement boilers every day lol. They would be giant piles of rust ;).
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No one wants a room at 180F. 180-100=80, comfy. We don't seem to be communicating very well, I'm the first to admit that I don't know the industry jargon very well and I could be misusing it.
 
Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
No one wants a room at 180F. 180-100=80, comfy. We don't seem to be communicating very well, I'm the first to admit that I don't know the industry jargon very well and I could be misusing it.
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No pretty sure we're talking water temp drop across the coil and a return temp that low will cause the unit to condense (flue gases) and that's a bad thing. I'm still trying to figure out what the gas law has to do with hydronic heating lol.
 
ttystikk

ttystikk

Well-Known Member
Budley Doright said:
No pretty sure we're talking water temp drop across the coil and a return temp that low will cause the unit to condense (flue gases) and that's a bad thing. I'm still trying to figure out what the gas law has to do with hydronic heating lol.
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Oh we are definitely NOT talking about the same thing!
1. No flue, not burning any gas for heat
2. The hot water in the coil does not cool that much, it flows quickly
3. My use of delta T refers to the difference between working fluid temperature and air temperature in the house
4. The chiller is outside and also does not use gas; it's just a compressor that pulls heart from a cold side water circuit and dumps it into a hot side water circuit

Clear as mud?
 
Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
Oh we are definitely NOT talking about the same thing!
1. No flue, not burning any gas for heat
2. The hot water in the coil does not cool that much, it flows quickly
3. My use of delta T refers to the difference between working fluid temperature and air temperature in the house
4. The chiller is outside and also does not use gas; it's just a compressor that pulls heart from a cold side water circuit and dumps it into a hot side water circuit

Clear as mud?
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i guess it was the 180 that confused me, is that what your supply water is, that's hot huh. I know your system quite well actually, we take it a step further and install air to water heatpumps for even more effeincy and control. Actually just touched base with one of the larger med grows in Canada about the system. Anywhooo I showed you one of the many residential air handling units I deal with that are blow through so that is why I assumed it really didn't matter and didn't think you needed to change your design but hey go ahead, perhaps you will find a new cutting edge way to redesign an airhandler. You should measure the heat removal of what your running now and compare. If you use the actual flow and delta t of the water it would be way more accurate ;).
 
ttystikk

ttystikk

Well-Known Member
Budley Doright said:
i guess it was the 180 that confused me, is that what your supply water is, that's hot huh. I know your system quite well actually, we take it a step further and install air to water heatpumps for even more effeincy and control. Actually just touched base with one of the larger med grows in Canada about the system. Anywhooo I showed you one of the many residential air handling units I deal with that are blow through so that is why I assumed it really didn't matter and didn't think you needed to change your design but hey go ahead, perhaps you will find a new cutting edge way to redesign an airhandler. You should measure the heat removal of what your running now and compare. If you use the actual flow and delta t of the water it would be way more accurate ;).
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Really I'm just a tinkerer. Water temp on the hot side rarely exceeds 110F and is usually about 100. That's why I need to use every trick I can to maximize the heat I get from it.
 
ttystikk

ttystikk

Well-Known Member
SSGrower said:
So could it be fan effeciency is the reason for push vs. pull? What's more expensive cfm or btu?
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No, Sir; as I said above, it's the delta T resulting from the change in pressure between the fan and the core, which acts as a restriction.

Pushing air compresses and therefore heats it. Passing that air through a cold core maximizes delta T, because of the extra heating between fan and core. Once the air passes through the core, pressure and therefore temperature drops. If that core is hot, then the pressure drop works against you in heating the air. The harder you push, the greater the effect and the less efficiently it will draw heat from the core.

Conversely, if you draw the air through a cold core then the pressure DROP between core and fan reduces delta T and makes it less efficient. Again; the harder you run the fan, the bigger the pressure drop and the worse it performs. If the core is hot, then the air, being colder due to the pressure drop, sees a bigger temperature change between itself and the core; delta T is larger and efficiency is improved.

This is why I suggested the experiment above, so you can see and feel the difference for yourself. It's not trivial!

If the BTus are free then of course CFM costs more.
 
SSGrower

SSGrower

Well-Known Member
No need for convincing look at an air compressor.
Making some sense now for the situation. In cooling (summertime house cooling) does the hot side still stay 100-110?
 
Budley Doright

Budley Doright

Well-Known Member
ttystikk said:
No, Sir; as I said above, it's the delta T resulting from the change in pressure between the fan and the core, which acts as a restriction.

Pushing air compresses and therefore heats it. Passing that air through a cold core maximizes delta T, because of the extra heating between fan and core. Once the air passes through the core, pressure and therefore temperature drops. If that core is hot, then the pressure drop works against you in heating the air. The harder you push, the greater the effect and the less efficiently it will draw heat from the core.

Conversely, if you draw the air through a cold core then the pressure DROP between core and fan reduces delta T and makes it less efficient. Again; the harder you run the fan, the bigger the pressure drop and the worse it performs. If the core is hot, then the air, being colder due to the pressure drop, sees a bigger temperature change between itself and the core; delta T is larger and efficiency is improved.

This is why I suggested the experiment above, so you can see and feel the difference for yourself. It's not trivial!

If the BTus are free then of course CFM costs more.
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ummm nope this is not a compressor and not a cylinder. Now I see where you were going with the gas laws lol. Gas laws pertain to an enclosed space not an airhandler :).
 
ttystikk

ttystikk

Well-Known Member
Budley Doright said:
ummm nope this is not a compressor and not a cylinder. Now I see where you were going with the gas laws lol. Gas laws pertain to an enclosed space not an airhandler :).
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Why not? Why should laws of physics apply in some places and not others?

TRY THE EXPERIMENT.
 
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