HVAC costs 1

[jdehoyos1]

New in this forum so please bear with me.
Is there an easy way to ballpark a cost to condition outside air to 72 degrees F under a handful of conditions (such as 80, 85, 100 degree air at 30%, 50% and 65% relative humidity)?

 

[friartuck]

There are lots of rules of thumb, but it depends on where you are, what type of system you want etc. Is it a large system or a small system, a one off room or several rooms...is it a chilled water system, a DX system etc

For one off rooms, a simple 'split' AC unit would suffice at around £3500.00 inc wiring

for a larger system, say a chilled water system with ducted fan coil units, etc, it may rise to £4500.00 per unit or more.

Also could you use rapid fixing methods such as 'Mapress' or plastic pipe such as 'Aquatherm', or are you restricted to steel pipe and screwed or welded fittings.

How long is a piece of string???



Friar Tuck of Sherwood

 

[blutfort]

I'm assuming that you mean first cost and not operating cost...

There is a lot more information that would be needed to
give you an adequate answer on this, most notably is how many CFM of air you are trying to treat and what your target leaving or space humidity is. Lacking that I'll try to give you some ballpark numbers.

Industy standard is about $5~$6 per cfm. How ever this is highly subject to total tons of cooling. On a small DX unit (3 Ton) you are probably talking about $18-$20 per cfm. On a 40 - 50 ton unit you are now in the $5 range.

How you doing the treating of the air is also a big impact on the price. If you need to nail the 72ºF on the head then chilled water is the way to go, but requires quite the infrastructure. You will also want to no doubt control humidity so you will need a reheat coil or a method of reheating the air following cooling it to 55º or lower to ring out the moisture.

Some jurisdictions do not permit the use of NEW energy to reheat air. An option there is to use a DX coil to cool the air to 55ºF and a parallel (or series) condenser coil to reheat the air. This can add $$ / cfm to your project in a hurry as well.

Hope some of this helped, but 100% OA is a beast to try and define. The more variables that could be nailed down would help get a better estimate on the price, but I guess that applies to most things in engineering!

 

[dUsTnUrTeEtH]

This maybe a little unrelated to the initial question but.....

If you were to raise the ventilation from 5 cfm to about
15 cfm.

How much would that cost you and how easy would that be to perform? Time to perform?

 

[dUsTnUrTeEtH]

its for school^^^^^

 

[ChasBean1]

Assumptions above seem to indicate installation or first costs, but your post indicates energy needed to perform the objective(?)

Q = m dH

after finding Q, then you'd account for efficiency or coefficient of performance (COP), etc.

Q is the evaporator energy (e.g., BTU/hr.)
m is the mass flow rate of air
dH is the change in enthalpy across the cooling coil

COP is the net compressor work divided by the Q...

 

[pavlik]

Based on my experience with contracts, $40 per square foot would be a good estimate of HVAC work.