Louisiana Humidity! HELP

bjl,
It sounds like you are making some condensate when your Units are running, as it should be with a cold evaporator.
Heating on a cold day will take more loop flow than cooling the house. Your loop will get colder as the winter progresses, but you'll have to wait until next winter to see that.

When you have things running the way you want them, you should consider the auto air removal Watts float valve. It may save your system from air binding one day.

Not being back filled would cause an initial warm water flow, but that should be pushed through the unit without causing a performance issue. It could be a safety issue if someone stepped into the hole or a pet got stuck.

Check your septic aerator for air flow into the house. I'll have to check how they operate, but I don't believe the air should be allowed to go into your house. That could become a health issue.

When you have more flow capacity, then you can check to see if the larger Unit somehow interferes with the smaller Unit. There are several people on this website that have 2 Units and they have a lot of questions about how they interact with each other over time. This becomes a question when the house won't stay warm after a few years of operation with no problems.

My Brother bought a digital amp meter and mounted it on the wall next to his Unit in order to monitor compressor performance at a glance. He bought the Daikin Inverter/Variable speed compressor which is the latest in Geothermal design, so he has all the temperatures, pressures and flows on the wall. He was telling me how this newer design is the way to go, but few HVAC people know enough to work on them, so he has made his Unit into a Science Project. He doesn't have the automatic variable speed loop pumps that are available since he is using an open loop design where we are using the closed loop design.

The Inverter Geothermal units have a 1 ton limit above the unit rating, so if you have a 5 ton, it can produce 6 ton. The Daikin was over $8,000 but should pay for itself in a very short period of time since it was a Hobby Install not a "$43,000 gonna get yur money back from the govment" with a 10 year payback deal.

I'm running blind for now with my Trane. I have cheap temperature probes that I put in the insulation to monitor water temperature and a few extra for monitoring air temperatures. I didn't like the idea of installing a football air valve/peach valve as some pros call it, in my unit loop inlet & outlets.

Keep me posted on how the Brutes work out, and don't let someone talk you into what they have on hand, buy them on line after spending some time watching the net for a good deal.

 

Guys, lets stick to the basics here.

Do you have a humidity problem or do your have a water flow problem? Nothing pointed to a lack of water flow on the source side, why are you changing pumps?
Your loop field temps seem OK for Southern Louisiana, so does your delta T on the water side. Measure your flow and your delta T, calculate the heat rejection and you know if your refrigerant circuit is within specifications. If that is the case, slow down your blower to reduce your air coil temperature, which will cause more condensation on the coil and will pull more humidity out of the air while providing similar cooling BTUs.
If this does not help your units are undersized for the cooling load. Either get your load down or get an additional dehumidifier.

This is not rocket science, this is geo 1-O-1.

 

Hi doc, good to hear from you again. Hope all is well. I know you probably don't remember me but you were a big help when I 1st starting walking down this road. It's been awhile though.

My excitement earlier was short lived. Water seemed to pour out of the air when I first got the units on this morning. I have not seen that yet. Before the units would run for several hrs straight and struggle to get into the low 60%s. This morning 1 hr from 73% to 62%. I did a few run tests today. Both units set to 64*, I ran them for 1 hr and numbers were 65* and 62% then let them sit for one hour temp rise was to 68* and 65%. Each time I did it, it was pretty much the same. Can't get past that 62% Main reason for this test was to unplug my septic aerator and see if air maybe coming in. I do have tape on all drains not hooked up yet, but I wanted to make sure. Also checked septic vent make sure wasn't submerged, .

How long should it take for a proper setup to reach proper humidity levels?

How fast should humidity climb on a tight house?

These units have a built in blower slowdown, but it's not functioning properly. I'll probably have to do it the old fashion way. In my 2 stage unit the dh mode contacts engage stage 2 and slow down blower. It definitely does something to the coppressor but nothing to the fan. After seeing the water fall out fast today, i'm pretty sure slowing down the blower will do the trick.

My big concern.
I designed this house around energy efficiency. It's not your typical build for Southern louisiana. And I've built 80% to 90% of it by myself. It's been 2.5 years and i'm ready to be done. The manual j called for 5 tons of system. Everyone around here likes "rule of thumb". I didn't design a rule of thumb house, but I let them talk me into up sizing to 6 tons. 2.5 ton single and 3.5 ton dual. Now that I've been running the system I'm thinking it cools to fast. And it takes an hour for the unit to turn back on. I think it's a 3* variance, which is easily adjusted. But it's only going to shorten runtime. I think 5 tons maybe to much. A 2 ton 2 stage and a 3 ton 2 stage would've been perfect.

What is each stage equivalent to, 1/2 ton?

One of the people that talked me into this is the salesman at the manufacturer. He said he doesn't know how much credit they would give me for the units I have but they would maybe assist with getting them switched out. I would do the switching so no labor on this end. Another option would be don't worry about the larger unit and change the compressor out in the smaller. For this I'll have to hire out.

Before making any decisions I'm going to do a few more run tests. If I warmed up the house to 75* then time the cooling stage to 72* (my wife's liking) would that give me a good idea of runtime? It'll be a few months till we see upper 90* temps, so I can't get a good idea of temp. Rise rate. and if I need to do something with the units I want to do it now since I've been talking with manufacturer. With 70* outside temp, my rise rate was 3* over an hour. I'm sure that'll worsen as the ambient temp goes up, but not by much with all the insulation. Blown cellulose btw.

 

Humidity is "relative" to temperature. 65* air at 62%RH contains the same moisture as 72.5* air at 51%RH. Your experience with RH rising with temperatures after a system run suggests there is still moisture in the building or it is infiltrating. During construction every porous material inside the envelope has had the time to absorb all the moisture it can. It is going to take along time to drive it out. As others have suggested concentrate on limiting (or disabling) second stage operation, lowering fan speed, and bring in dehumidifiers until you get the humidity under control.

First stage is 2/3 of full capacity of the unit.

 

bjl,
The 2 stage compressors are actually a scroll compressor with a bypass orifice. Operating in 1st stage the orifice bypasses 1/3 of the compressors Freon thus capacity.

During 2nd stage operation, the Y2 signal from the thermostat which is set around 3 degrees off of thermostat set point, will energize a coil in the compressor that will lift a ring/hoop that closes off the orifice, increasing capacity of the compressor to its full design tonnage.

You said: "My circ system is 2 grundfos ups 15 42f, 1 for each unit".

What do the Pro's have to say about the use of UPS 15 42F as circulating pumps for bjl's loop design?
How about a flow rate below Unit design with two of them running?
My common sense tells me this is bjl's problem.
Would it be wise/efficient to operate on the low end of Unit design loop flow?

 

So what is the flow rate? How do you know that the flow rate is low?

What is the flow rate with both of them running? And why would the flow rate cause a lack of dehumidification?
All we know is the reported 10F delta T on the source side. So lets see, I am getting rusty in this:

HR (capacity + Compressor BTU) / (delta T x 500) = GPM

42,000 BTUs + 10,000 BTUs Compressor / 10 x 500 = 10.4 GPM

Just some ball park numbers meaning you have around 3 gpm/ton. Why isn't that enough flow for a 3.5 ton unit? And even if you would have lesser flow, why would that cause dehumidification issues?

 

bjl's first flow test was 6.5 gpm As Found, so he put the 2nd pump in series and made this response:
"I took a couple hours today and threw that pump inline. Wish I would have read your post before doing it. I sure thought if would give me more gpms than it did. With both pumps wide open, drumroll, only 9.5 gal. Still a gal. Shy of my specs."

On my Trane 4 Ton Unit I replaced the 2) UPS15-58FC pumps with 2) UPS26-99FC Pumps, since my compressor tripped after a few minutes due to low flow. The 3 speeds will allow fine tuning power for winter and summer use after I install a permanent Amp meter on my compressor for a quick indication of efficiency.

Knowing the flow results might help narrow the problem down to the loop flow.

Having 6.5 gpm would cause the units to run for long periods of time slowly dropping the house temperature. With both loop pumps running the condensate started flowing rather than sitting in the tray.
If you consider what others have said about humidity taking some time to come down with a new construction, I believe bjl will have better results with more loop flow capability.

 

I really do not take this method of measuring flow serious, thus the 6.5 gpm are highly questionable. The delta T and the 5 PSI delta P (even assuming 4 PSI delta P, accounting for the line loss to and from the heatpump) suggest much higher flow than 6.5 gpm.
Again, you need to elaborate for me how the low flow will change the cooling capacity of a geo heat pump. 3-4 gpm less for a 3.5 ton HP will increase to leaving water temp slightly (3-4F), meaning the average water temp in the coil is up by 1.5-2.0 F, which will decrease the total cooling capacity by less than 3%.
I do not have the Miami Heat pump expanded performance tables, but attached is the performance table for a Waterfurnace 3.5 single stage unit. At 80F EWT thand 5 gpm flow the total cooling capacity is 41.4 KBTU, and at 11 gpm 42.6 KBTU. So doubling the flow results in less than a 3% increase in capacity.

So you are very wrong stating that a flow of 6.5 gpm would cause the units to run for a long period of time. This is not the case. And you are completely off stating that the "condensate will start to flowing" when both circulation pumps are running.

If your own 4 ton heat pump tripped on (2) 15-58 in series you have a significant design issue with your loop.

Again, source flow does not change capacity significantly and is irrelevant for the lack of dehumidification!

The only way to pull more moisture out of the air is to make the coil colder so you have more condensation. Either you stage up the compressor in a multistage system, or you slow down the blower. Flow in the loop field does not do anything!

 

Well doc, this topic is getting very long as you have mentioned to me before, but if you go back and read all of what bjl has written, you will find that everything you are questioning from my post was written by blj in his posts.

 

Not really. You were suggesting that improving the flow will have a significant impact on the dehumidification or the cooling capacity of the geo unit, which is not the case. But it will increase the pumping power without knowing what exactly the flow is.

 

"During construction every porous material inside the envelope has had the time to absorb all the moisture it can." Geoxne said.

"2x6 exterior walls with wet blown cellulose." bjl said. If you have cement slab floors that's a lot of moisture as well.

Why not rent some dehumidifiers. They will introduce a little cooling load as well.

It sounds like the ground loops would not be as warm as they are if you hadn't been trying to cool the house to 65*F.

ChrisJ

 

Sorry, I haven't been able to work on the house much with this big job we landed. Been working days and most nights trying to keep it running.

I know it'll take prob over 6 months for the house to fully dry. My concern was flooring with high humidity. I bought a humidity meter and it finally came in. My thought was infiltration though i know the envelope is sealed, and I can pinpoint where with the meter. When I 1st turned on the units humidity was in mid 70's. After 30 min it was mid 50's. Left the meter in the kitchen and came back later, 52%. It also said temp was 64* though t/s were set at 66* and reading 68* in room. T/s was also reading 63% humidity. I put the meter sitting on the t/s, meter read 52%, t/s 63%. What gives? I can understand a 1 maybe 2 variance but 11%. What am I suppose to believe. The overpriced, supposedly top of the line t/s, which one of the humidity sensors have already gone out. Or the inexpensive meter from amazon, AcuRite 00613A1 Indoor Humidity Monitor.

Doc, I know this way of measuring flow is crude to say the least. I did order a simple flow meter that I can put inline and remove once I have accurate flows. I did the flow test several times and each time was the same.

If this meter is correct, the only problem I have is a t/s one. Do I buy a 3rd meter to figure this out?

After I filled in the last 20' of loopfield. Where it enters the house. The ewt seemed to have settled around 74* or 75*. This was just a thought to maybe increase efficiency a lil. All 8 of my field runs through one 4" conduit to my attic. Would it be worth the additional pump power to send my condensate to drain down this line to further cool the ewt? Or even the lwt?

 

Welcome to the world of imprecise measurements, where you never can be sure what is really going on!

The #1 rule to successfully design a geo system....is to keep it simple.

 

I stopped by the house on my way to another night shift to check humidity. The cheap portable meter was showing 43% which seems low to me and the 2.5 ton t/s was reading 55%. The 43% was in the kitchen in the 3.5 ton zone, which according to the t/s has not run in the past 18+ hrs. The 2.5 ton read it has ran 6 of the past 18 hrs. An average of 20 min per cycle seems pretty good.

I guess I need to sucks it up and buy a decent portable humidity meter to see which one is wrong.

Very good advice. I spent a butt load of money on relays and circuit boards and designed a schematic to where if the water is low or a pump burns up, that unit will not turn on. None of it is working at the moment. I had no clue a conductance style low water meter will not work in distilled water. The circuitry was supposed to run from it.

 

bjl,
Using the automatic air removal float valves in your loops high point will keep the air out of your loop eliminating that as a cause of loss of loop flow. If a loop circulator pump trips, your Units have low flow protection circuits built in shut down the compressor which you can see in your Units Functional Schematic.

The high level condensate pan Compressor trip uses the conductance of the water in the pan which is close to distilled with some air impurities in it, and it conducts well enough to perform the trip function. I figure the water you are measuring for the trip would be as conductive as that in your pan. I believe your sensor will do the job you intended it to do.
When your Units trip on a low flow trip, they will lock out a restart until the problem is corrected and power is cycled to your unit.

The increased flow of a 2nd pump has improved the efficiency of the smaller Unit, but the larger Unit must have locked out since it hasn't run for 18 hours with a signal to start from the thermostat.
Change out your 1/25 hp loop pumps for 1/6 hp loop circulators. Be careful not to get distracted and go in another direction until you eliminate your flow problem.

A 1/25 hp pump sells for under $100, it would have been great if they had worked in my loop. The $250 per pump 1/6th hp pumps will give you the flow rate capability you need in all situations, heating and cooling.
I noticed that several of the Geothermal Flow Centers use single speed UPS26-99 pumps. That leads me to believe if an installer was to make an error in the set up of a loop, it would be erring in the overdesign of the loop flow rather than under designing loop flow.

 

Usually a thermostat does not know if a heat pump is running, unless you have any of the bus thermostats from waterfurnace, which are usually not applicable for single stage units. Thus the thermostat only know if it has given a 24V signal, not if the unit was running. Thus you cannot conclude from the thermostat not calling for cooling that the heat pump is locked out.
Nor is there any evidence that there is low flow. 6.5 gpm on a 3.5 ton unit would not cause a low flow lockdown. 10F delta T on the source side indicate enough flow at 79F EWT in cooling mode, unless there is something wrong with your refrigerant circuit.
Do not switch out pumps before you don't know the facts where your flow is. Increased flow only has minimal effect of heat pump efficiency, but can cause a significant increase in electrical consumption.

 

it sounds your question is every professional. it is beyond my understand of the normal humidity monitor.