Some background information. I have a degree in mechanical engineering, so I completely understand the theory. The calculation of the loads were done as follows: - conductive heat transfer, done as a careful U A ÎT analysis using HDD & CDD (I used +35F for the insolated roof temperature); the roof has little shading, but the east and west walls have a good bit of shading, and the roof has long eaves, and the solar elevation angle is very high in the summer, so I did not use this factor for the walls); I used an effective R-value of 4 per perimeter length for the slab (admittedly this is something I would like to get a more accurate determination, but it seems that for a warm winter, it is not a big deal) - window insolation, done using the insolation constant and expected normal angle and time (because of the excellent eave shading, this is very small); there are some larger east windows, but that is in the morning when the other heat loads are small - internally generated sensible and latent loads (only the appliance sensible load was large) - infiltration, as an expected exchange factor times the volume of the conditioned space, with the sensible load as the mass times heat capacity time temperature differential, and the latent load as the mass of the air times the specific humidity at the design wet bulb times the heat the evaporation (the determination of this exact value of this exchange factor seems to be problematic) I don't think I missed anything here. Like I said before, the big question mark is the infiltration factor, which has a large impact, especially on the latent load when the wet bulb temp is 81F! But in any case, if because of the good sealing from the spray foam insulation, my home is so well sealed that I need an air exchanger, then I should just do my calculations based on what this net air exchange would be (a good value seems to be about 0.4, which is indeed what I used here.) I tend to agree with daddo. An HVAC unit should be able to handle the proper dehumidification itself at peak loads. But I have heard that when a unit is sized too large, that there is a problem with keeping the space at the proper humidity - and by definition, for any time that is NOT peak load, the unit would be sized too large. I have never personally heard of anyone in my hot humid area that had a special dehumidifier - the standard HVAC unit always sufficed. But anything that would give me more control over the thermodynamic properties is always a plus.

My compressor also went 1 1/2 weeks ago. I was not too upset at first because I was leaving to go to the Cape. However, I cannot stand the heat since coming back and I finally broke down and had a HVAC guy come out. It is the compressor as we thought. The freeon is full. The label on the outside says it was made in 1989 so I guess at 22 years old it lasted well. We bought this house 2 years ago and it seems everything has recently started to need to be replaced. We will be having our roof done soon. Anyways, my question is also whether I should just replace the compressor or update to a new energy efficient a.c.. The a.c. we have now is a HEIL. My furnace (oil) is a thermo pride and I believe it was replaced in 2007. The house was built in 1984. It is a raised ranch with a up and down in-law that does not run off this furnace (it has its own gas furnace). There is also a lower level apt. that is also seperate with it's own furnace (oil). However, my apt. space and the lower level tenant share the same oil tank. We only have central air. The in-law and lower apt. do not. I think my a.c. unit is a 1 ton. The service man quoted me $800 inclusive to put in a new compressor. He also said he had an old ? 6 years model a.c. (not just the compressor)that he recently took out of someones place when they updated theirs for a more energy efficient one. He said he'd give me a 1 year warranty and it would cost $5oo.oo for this used one. I did not ask for a quote on a new one because we need the money for the new roof He is suppose to be calling me back to let me know for sure the age of the old unit. Any advise would be appreciated. Sue

Im a master plumber of 22years. pex is not the answer. pex breaks down with chlorine, UV, and high temperature. 99% of modern plumbers have no experience, they are truck jockies and salesmen, copper can last 100years if installed correctly. when installing pex you can not use a torch within 18” of the pipe. crimp rings slide off the barbs, the pex will burst like copper when frozen, a sharp edge on a light fixture can rub a hole. UPONOR makes the only reliable fittings they are $30-$45each solid brass connector and ring specialty tool to install them using expansion and compression, however however, there are precautions with installing copper. copper needs dielectric consciousness, avoiding concrete, a screw can go through any pipe, they make nail plates per code for passing through a stud in a wall. Pex is for lazy guys who dont want to get dirty. it has certain applications such as non-potable water, radiant boiler heating lines, irrigation for plants. trustworthyplumbingllc@gmail.com i will answer any questions at no charge.

John, Thinking back when we were doing major renovation (a total gut job) I was trying to get the sheet rock guy to come back and finish. He apparently had a deal with the plumber when someones ceiling caved in the plumber fixed the leak part and then wanted the sheet rock fixed pronto. They left whatever they were doing and fixed the ceiling. The plumber must have paid them a premium. Don't know if it was due to pipes pitted or leaking but that kind of thing happens a lot I think. Is there a way you can crawl up there and inspect the plumbing yourself? If you don't see any leaking, probably nothing to worry about right now. If it happens at some time and your ceiling caves in because it's soaked, realistically it's not the end of the world. OK I'm not making light of the situation but it's all fixable as long as you're not off on a 2 year cruise while things rot and mildew. It will not do major damage other than your pocket book.. Replace plumbing and sheet rock, then paint. A PITA but not serious in the greater scheme of things. I hope you can figure it out because thinking and worrying about what may or may not happen can often be worse than the actual happening. I also hope crawling up there is easier than in our house. When I was 50 no problem, now not too keen on crawling thru insulation etc making sure I don't fall thru the sheet rock where there's no plywood. If you can't do that maybe you can find a trusted young person with some maxi to do the inspection. I'm pulling for you.