"One system we specify was a contractor suggestion. The "old way" was board insulation and so-forth, pretty common but with a covering of roof membrane to match the roof material. That worked great except it was not a sanctioned application…"
"That is why I like VRF systems, David. We agree especially in the humid south and of course with cycling in general of on-off single-capacity systems.
Inverter drives are the current ideal and I use them whenever I can on larger systems (which…"
"Got it and understood thank you. I was figuring if there was a problem, the water was not leaving the unit.
That amount of moisture though is negligible though, at least in large, high-latent air handling units.
For example, a 10,000 cfm 100% OA air…"
"All cooling coils which remove moisture (which is most of them!) require a drain pan below them to capture this. So much is known and ideally this would be either stainless steel or an approved thermoplastic or ABS for corrosion protection. The…"
"This has been a topic of discussion for 20 years now. It is true that appliance manufacturers often sanction PVC (solid, not cellular core as Charles Buell noted), as venting material. This keeps cost down and market share up and there are thousands…"
"Looking at that graph, Allison, the high RH period of five days looks like a vacation period perhaps? With AC setpoint at a higher temperature?My thinking is that, aside from contributed fan heat, running the fan is enthalpy-neutral. There may be a…"
"Agreed! True, if an open plan. Simple is best. But away spaces seem to be making a come-back. And as others noted, return air pathways, let alone directly-ducted return air to each room, is rare indeed."
"Qualified "It Depends" kind of answer.
1. Temperature Perception:
There is an intangible comfort advantage to "Fan-On" in that it obviously provides continuous circulation. In a tight, modern house, there is a certain…"
"I am partial to my Leica Disto D330i but also agree with the caveats you state, especially on bright days. Once you get the hang of it, using the area and angle functions, it speeds things up. My principle application is take-offs for blower door…"
"I would use an in-line backdraft damper such as Artis Industries or the ones made by Fantech and other ERV/HRV manufacturers. The Fantech ones are mildly spring loaded but have a low pressure drop that I have measured at less than 0.04 inches…"
"Excellent article. We have in our engineering practice a section on protection of electronic devices. While public bid laws rather constrain us, we are partial to Price-Wheeler "Brick Wall" surge suppressors. Very robust and simple units…"
"One of my several skill sets (I really hate that term, it harkens to nursery school!), is commissioning. By day I am an HVAC design engineer and PM but oversee projects from conception to completion, so it comes with the territory.
My side work is…"
"All good points and refinements, Tedkidd- and by the way, call me Brad. And yes, I am a confirmed wet-head but also a dry-head on commercial/institutional projects more than residential.
Anyway, agreed that the business is moving BTUs and not to put…"
"Agreed, the loss is relatively constant (save for the differences in temperature, narrowing during milder weather and widening with cold, thank you).
As you note, improper sizing coupled with poor duct locations are often existing conditions with no…"
"I see now what you mean.
Agreed that installing any ductwork outside the thermal boundary unnecessarily, should be avoided.
But to take this a step further and by the numbers, code minimum for insulation on ductwork outside the thermal…"
"I can offer some empirical information, general and highly variable, but borne out with regularity.
The "cycles per hour" metric we understand is applicable to on-off equipment of fixed capacity; at best and often rarely it is most closely…"