Engineering my Infinity to be an on demand dehumidifier
OK, the problem is my humidity is not controllable even with my 2 stage Infinity 50/100. At times the humidity goes past 60%-70%. Homeschooling 5 children with three meals a day may have something to do with it.
I am going to engineer the system in this way: Install a valve(probably using a reversing valve) to send compressor discharge into the air handler through a coil and back out to the regular condenser. Essentially making the system into a dehumidifier that only removes humidity.
The controls will work to keep the system in first stage when I do this.
Question....how big should the coil be that I install inside the air handler?? A 1.5 ton coil just seems to big, although that is the capacity of the system in first stage. The coil I have(1.5 ton evaporator) will not fit, so I was going to make it smaller.
I am not worried about static pressure loss...my duct work is running at .3 TESP right now with filters..it is perfect.
I think by the time you added up the cost of the coil, extra lineset, valve, wire and your time to pipe this all in... you might as well just spend $$$$ on a whole house dehumidifier.
You could also instead get a tube and shell heat exchanger and make warm water, then install a hydronic coil to reheat the air. Less copper piping, and you could use the hot water for preheating domestic hot water.
Do you have the Infinity controller?
You hit the nail right on the head. It'll only get worse as cooling demand decreases as we progress more into the fall and winter. If you have a tight home, even more. I hear you on all the engineering ideas... It's going to consume a lot of time and $$$ by trial and error.
Originally Posted by ChaseAir
Do yourself a favor and get a ventilating dehumidifier. Let your A/C control your sensible, and latent during summer operation, and let your dedicated dehumidifier control your latent during the three no-cooling seasons.
That many occupants inside all day also really requires fresh air ventilation, something you will need to consider if you plan to continue your 'engineering project'. A ventilating dh already has this plug and play. The Ulta-Aire line is what I'd recommend. The DEH 3000 control would be the way to go for you.
I'm a believer as I have one in my home and no longer put up with high RH, and all the 'funk' that goes along with it.
Thermo John, you brought a tear to my eye.
Originally Posted by thermojohn
See if I can add to this wisdom.
On start up, the a/c cooling coil starts collecting moisture until the coil/pan loads and moisture starts down the drain. It takes 20-3mins. for moisture to start dripping down the drain. Most coils collect l lb. per ton prior to start draining. At the end of the cycle, the moisture left on the coil re-evaporates back into the ducts/home. Fan on "low", the moisture is back into the home in < 1 hour. Fan "auto", it takes <2 hours. One lb. of moisture humidifies 1,000 sqft. of home 8%RH. A 3 ton coil holds 3 lbs. of moisture at the end of cycle. This is the problem with using the a/c as a dehumidifier. Assuming you have reheat on your a/c as you propose and dehumidifying the home down to 50%RH, mositure left on the coil re-evaporating from your coil will raise the %RH to 58%RH during the following hour or two. Another negative is that the you only get 1-2 lbs. of moisture per KW using reheat from an a/c.
The Ultra-Aire dehumidifier removes 4-8 lbs. per KW depending on the model.
First issues is to setup the current a/c to do it's best. This means adjusting the air flow of the air handler blower to remove the proper amount of moisture while it is cooling. Slow the air flow to get a 45 to 48^F cooling temp. This will provide 75^F, 50%RH during the hottest times of the day while your a/c is running alot.. Anytime you have a couple hour cooling run with your a/c setup like this, you should endup with 50%RH.
During evenings and during rainy cool weather, a whole dehumidifier is a must.
If you must continue on your path, check out the Lennox Humiditrol concept. They have the limitations I described above. Better to use a whole house like the Ultra-Aire. The ventilation option has much merit. If you are interest in more discusion, continue posting.
Keep us posted on your results. Excess air infiltration and incorrect a/c setup explains not being able to get <50%RH during high cooling loads.
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
If you were going to engineer it yourself you'd need to upsize the FCU and tune the fan speed.
The other options that I would suggest would be checking out Carrier's Infinity ERV's. If you go with the Carrier ERV you'll be able to control with your existing Infinity control. The ERV part numbers are (ERVCCLHA or ERVCCSHA or ERVCCSVA) depending on your configuration.