water temps and hydro air

Unknown

Got a link?

[Deleted User]

water temp and hydro air units

How many of you guys are designing hydro air systems to run 140 temps or lower.I am trying to convince a new customer that you can run lower water temps thrue the coils and still have plenty of comfort.

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Wayco Wayne_2

I'm doing it

in my own house. I designed the water coil for 140 at design temps and am running the water temps with a Munchkin 140M. Works great. Saved lots on my gas bill too. WW

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Jeff Lawrence_25

I Have one

The customer is an engineer (groan) and says the 120° water temp supplied by the WSHP will be more than enough for his heat needs.

r i g h t

I made sure the air handler has 10kw of strip heat in it.

Unknown

sizing

if the coil is sized for 120 it shouldn't be a problem, most (all?) fan coil manufacturers have correction factors to derate the output. i do many geo installations like this and they've always worked well.

Unknown

If you install the correct size coil it works very well. In our case we sized the coils to deliver the proper amount of chilled water for cooling the various spaces they serve which makes us way oversized on the coils for heat. I ran 110* through them on low fan speed all last winter as a supplement to the radiant floor warming and the air coming out of them actually felt pretty warm. I am using a new style air to water heat pump which allows me to work with such low water temps and not have any detrimental effect on the units. We're still experimenting with temps too BTW but 110* seemed to be doing the trick for us.

[Deleted User]

140 and less

We use adp units and they have a sizing charts for 120 and up. We have sized for 140 using outdoor reset and have had great results with comfort and fuel savings. The building is going to be built very tight with foam insulation so i think there would be no problem but others disagree.

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Unknown

Yes, so far the foam insulation has proven to be quite remarkable in the house we did, it's like a giant styrofoam cooler. The real test comes this summer though, when we see if the cooling keeps up. I think it will but there's always that grain of doubt until it does.

Brad White_172

Entirely Possible

As others have noted, you can select a hydro-air coil for nearly any water temperature higher than your desired leaving air temperature.

Key aspects are the number of rows (1-2 are standard offerings; I sometimes specify 4 or even 6 rows).

The other side of the coin is the temperature of the air and how much of it you need. As you can imagine, less-warm air requires more volume. There is a point where humidity plays a role too. Where these come together is where you have a dry house (20% RH or less, say), are running very low air temperatures which, on paper, will heat the house. The air may be 90 to 95 degrees for example. You wind up moving so much air that it actually feels cool to the occupants due to skin evaporation.

My suggestion is to size your heating CFM for temperatures of between 100 and 105 degrees minimum. This is subjective but you should have a means of balancing and adjustment.

If you size for colder air, you will groan worse than Jeff when he mentions engineers.

Nron_13

HYDRO AIR

I used a Rinnai Instant water heater in my moms house with an enerworks fan coil set at low fan speed the temp set at 120 and It runs fine to about -24F then it needs to be increased to keep the cool air effect mentioned from happining , we have low humidity in alberta

Unknown

Geo guys size air handlers for less than 120 all the time. Alllll the time. why so skeptical?

Unknown

I'm reading this tread with great interests

I have a upcoming job that customer said that I'm only one can give straight answers... His heating unit is wm gold gv,
He have radiant floor heat, air unit in garage and 2 ahus , one for each floor.. His basement too hot, no mixing valves, his 2nd floor tooo cold... Boiler max temps is 140... So I recommeded heatinging exchager for the ploy tubing radinat heat.. And mixing valves to same while ramp the higher temps to the ahus... Before I do that as reading this thread.. The ahus may not have enough coils to runs it lower temps...

Mike T., Swampeast MO

And ideally, the blower would be variable-speed and under direct control of the boiler "brain" or add-on "brain" controlling the boiler. Why? You'd be able to use a somewhat steeper reset curve (more like with true hydronic emitters) without having a problem of "blowing cold air" in moderate weather.

It's been about a year since I did conducted a fruitless and hardcore search for such an air handler. Perhaps things have changed (or I missed something) but the VS air handlers I found were all tied to dedicated thermostats incapable of "talking back" to the boiler.

Perhaps Tekmar has addressed the issue. I really don't know but since the now have an offering (TN4) that can directly control the Vitodens, they might have anything...

Wayco Wayne_2

Mike!

I put a Taco 00 Variable speed circulator on my hydro air coil at home. It has a sensor in the supply duct. The circ speeds up and slows down to meet a temperature setting for supply air. Worked very well. I know you are thinking of varying the fan speed but this works pretty well. WW

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colin_4

hydro air

SummerAire makes air handler with vs blower and vs circ built in. Apparently will modulate up to increase heat output via programable time delays. Also controls blower during cooling to optimize dehumidification. I have not used one yet, just found out about them, but they look interesting. www.summeraire.com

Keith_8

Wayco!

Is there an outdoor or indoor sensor ramping up & down the pump to maintain discharge air temp?

Keith

Nick S

Fan Handler

I have job coming up that I plan to use a heat pump with hydro coil for back up. I plan to use a standard non ecm air handler with a Fan Handler control. This thing is pretty cool, it modulates standard psc motors with a sensor located in the supply duct. So with outdoor reset the airhandler will always supply the same temperature air (lower water temp= lower fan speed). The control works the same way for AC by lowering fan speed to control the latent load, then the fan speed increases when latent is under control.

Nick S

I am a moron when it comes to computers, so I don't know how to post a link, but the site is fanhandler.com. I have not used the fan handler yet, but I have used thier head pressure controllers with success. There is a lot of good info on the site.

Unknown

Thanks, I'll take a look...