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Discussion Starter · #1 ·
Hi guys and gals, I am going to be building a new home in the near future and we are looking for different ideas for HVAC.
Radiant and mini split is ruled out as the customers want to utilize a wood stove in the great room and fear that the radiant won't be able to respond quick enough.
A conventional hot air system with electric heat pump and hot water boiler back up was brought up, it seems to me a bit pricey to have redundant heating systems.
Baseboard hot water and a central air system is a possibility but the windows are pretty close to the floor so I'm not sure if base board will fit.
My plumber/heating guy suggests a high velocity system.
What are your opinions on the high velocity?
thanks,
dave
 

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One builder I work for uses them exclusively, he thinks they are the best thing since sliced bread. I'm not crazy about the look having little vents all over every wall...kinda like wall acne.
 

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If they want to use the wood stove as a primary heat source you are probably stuck with forced hot air with a large return air in the room with the wood stove. They can turn the fan switch to on instead of auto to circulate the heat from the wood stove throughout the house.
 

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First, an ACCA Manual 'J' heat load. This will determine the size of equipment, including wood stove.

Response time of hydronic radiant systems is relative to the heat loads and controls. With outdoor reset and other intelligent controls response time is irrelevant in most applications. Radiant ceilings have a higher response time than floors.

We use high velocity, Unico, SpacePak etc. since the bulk or our business in radiant and we have no problem integrating solid fuel with gas, electric or oil.

Backup or primary heat can be a gas-fired water heater driving a 4 row hot water coil in the high velocity unit.

If they want burn would a full-time fan will be in order.
 

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Back when I sold residential HVAC, we installed a couple of HV systems. Both were in really old homes with VERY limited space to run "normal" ductwork. It's more expensive on the front end due to the higher cost of the special air handler and ductwork. But, you won't get a better system for dehumidification.

I don't remember exactly why, but IIRC, it has something to do with the velocity of the air and the correlation of the amount of air crossing the evaporator coil, being substantially higher than in a regular forced air system.

As for the "acne" and "vents all over the wall comment".... I don't understand that one. With a HV system, it's common practice (at least it was back then) to put the 4" round supply vents in the ceiling (usually in or near a corner). And, I can't remember there ever being more than two in a room.
 

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Back when I sold residential HVAC, we installed a couple of HV systems. Both were in really old homes with VERY limited space to run "normal" ductwork. It's more expensive on the front end due to the higher cost of the special air handler and ductwork. But, you won't get a better system for dehumidification.

I don't remember exactly why, but IIRC, it has something to do with the velocity of the air and the correlation of the amount of air crossing the evaporator coil, being substantially higher than in a regular forced air system.

As for the "acne" and "vents all over the wall comment".... I don't understand that one. With a HV system, it's common practice (at least it was back then) to put the 4" round supply vents in the ceiling (usually in or near a corner). And, I can't remember there ever being more than two in a room.
All the HV systems I've seen use 2" insulated ducts.

http://www.hi-velocity.com/

http://www.airmaxtechnologies.com/maxair.html



 

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Discussion Starter · #14 ·
thanks for all the replies!
The more I learn about the high velocity system the more I think it will work well for the customer. With the use of their wood stove and the blower running all the time it should keep the house comfy.

Just a bit more info on the home. Single story 9' ceilings, SIP walls, lots of south facing good quality windows, an open floor plan.

thanks,
dave
 

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Why can't one use a standard air handler or furnace on a h.v. setup?
IIRC.... the HV systems operate at and have a MUCH higher CFM capacity than a regular air handler or furnace. Which requires larger evaporator coils as well. A blower from a HV system would blow the condensate off of a regular coil back into the ductwork.
 

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IIRC.... the HV systems operate at and have a MUCH higher CFM capacity than a regular air handler or furnace. Which requires larger evaporator coils as well. A blower from a HV system would blow the condensate off of a regular coil back into the ductwork.
HV have much thicker evap coil and move a lot less CFM then a conventional system does(roughly 50% less). Due to the small trunk/plenum line and supplies, the blower motor has to be a higher HP to move the air through the very restrictive duct. The supply side static alone exceeds 1", and is often as high as 1.75". Add the return and air filter in, and your above 2" of static.

HV systems don't cool the room/house by exchanging all the air in the room/house, but rather by aspiration/mixing of the room and HV air.
 
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