HRV complaints

Mike Lampkin_2

I'm looking for ideas to temper the incoming fresh air
from a HRV, which is moving about 200 cfm.The heating system
is a combination of infloor radiant and an air handler,
which the HRV feeds into.Rather than using an electric duct
heater, would it be worth while dumping the HRV fresh air
to an unoccupied area of the basement which is heated by infloor radiant, so that the fresh air would be tempered
before it is sent to the air handler?

Weezbo

No i dont think so.

either balance the system,or get a coil that is set down around 40 below zero to operate .... then when it gets 40 below zero the recirc on the coil starts moving the anti freeze about through a boiler loop connected to a heat exchanger...then when it warms up your system will be sending warmer air into the building through the hrv:) van -e's have dampers so they wont freeze up.

jwade55_3

A couple of questions.

You mentioned that the air from your HRV feeds into you AHU, how is this configured? Secondly what percentage of your total design airflow is your 200 cfm, and is this air ventilation or make-up? Does your AHU have a heat source?

My thought is that if you have a heat source, maybe you can use this to condition your fresh air.

J

BillW@honeywell

Try a reheat coil...

You can use an hydronic coil to temper the air coming out of the HRV. HRV's are about 70-80% efficient, so on a really cold day, the discharge could be chilly. Set the coil up with a zone valve, and a control that will lock it out until the OA temp drops below 32 degrees. All you are doing is warming the air, so you don't need to size the coil to do more than that. Also, the hrv should discharge from louvers high up on the wall, so that it will not directly discharge on occupants. If it is going to be exposed to sub-freezing temps, either a freezestat or glycol must be provided.

Operate the HRV on low speed 24/7, but allow provision for it to be manually set to higher speeds when the space is occupied for a party or other larger than normal demand like cooking, smoking etc.

Mike Lampkin_2

Thanks to everyone for the replies...

I have decided to go with the reheat coil to temper the
HRV air.Thanks for the good advice.

Steve Eayrs

Where is the air dumped into the building??

HRV's work great if the air enters the room up high on the walls, where it can mix w/ the room air, but creates cold drafts in dumped into floor registers.
Yes it can be somewhat fixed with coils and such, but if done right and ducted out the walls up high, its not needed.

Steve

Paul Pollets

Supplemental heating coils

Lifebreath makes 6" and 7" inline electric coils for their HRV's, built in thermostat and sensor. A 3500KW heater is very reasonable, price wise. HW coils cost more to install, but less to operate.

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Mike Lampkin_2

Thanks Paul...

I will give Lifebreath a call about their electric heaters.
Do you know happen to know if any of the HRV companies sell
prebuilt hydronic coils with the bells and whistles already
installed?

Mike Lampkin_2

Up in the frosty north..

When it gets to -30 degrees, I have seen standalone HRV's
still throwing out some really chilly air, even with the
high wall registers. I agree with you that the placement of
the registers is very important, but even doing this still
caused customer complaints.Thanks for the reply.

Mike Lampkin_2

HRV's and hybrid heating..

When designing HRV's into homes, with a combination of
radiant infloor and air handlers, would it be better to
use a complete standalone HRV system, where the HRV is not
tied into the air handler? There would definitely be less
air movement by not having the blower on the air handler
running whenever the HRV is running.The big advantage of
using the air handler with the HRV is that you can use the
same ductwork to distribute the fresh air to all of the
rooms.Which method would you use???

S Davis

HRV

That is the way we do it, and by running multiple outlets throughout the structure you cut down on the CFM per outlet and avoid some of the draft issues, we usually run between 6 and 8 outlets on a 200 to 300 CFM unit.
And dump them into areas people will not spend alot of time like pantries and closets.

S Davis


Apex Radiant Heating

Weezbo

Stand alones..less hassels.

Hrv is not much of a match for an existing oil fired forced air furnace although it can be done i dont recommend it due to some nasty results that have been recorded the house if it is two or three stories can become unbalanced Inside

Adam_6

> I'm looking for ideas to temper the incoming

> fresh air from a HRV, which is moving about 200

> cfm.The heating system is a combination of

> infloor radiant and an air handler, which the

> HRV feeds into.Rather than using an electric

> duct heater, would it be worth while dumping the

> HRV fresh air to an unoccupied area of the

> basement which is heated by infloor radiant, so

> that the fresh air would be tempered before it

> is sent to the air handler?



What about using a chilled water loop to temper hot air during the summer? The heat pump I'm looking at claims to be able to produce the hot water for the radiant floor, but can also produce chilled water (44 F) during the summer. I've actually thought about forgoing central air since I only need about 1 Ton of cooling capacity if a system like this would temper the air sufficently. It seems like this might work, but every guy I talk to doesn't really know much about radiant systems, let alone the heat pump or HRVs.

Adam_6

What about using a chilled water loop to temper hot air during the summer? The heat pump I'm looking at claims to be able to produce the hot water for the radiant floor, but can also produce chilled water (44 F) during the summer. I've actually thought about forgoing central air since I only need about 1 Ton of cooling capacity if a system like this would temper the air sufficently. It seems like this might work, but every guy I talk to doesn't really know much about radiant systems, let alone the heat pump or HRVs.