Tag Archives: research

3/8 inch and flowing

“I told you so!” – was coming to my mind while looking at the plumbing in a Swedish single family home built sometime in the 1970’s.

Some plumbing lines were partially exposed to keep them in the interior conditioned space. What caught my eye right away was a 3/8 inch branch (or twig) coming off of a 3/4 inch trunk line.


The use of 3/8 inch plumbing lines (or twigs) fits right with the material and energy conservation goals of an efficient domestic hot water delivery system, as was explained to me by the hot water guru Gary Klein. The problem for us in Chicago is that the smallest allowed pipe diameter per plumbing code is 1/2 inch. The rationale behind this limitation is, so I assume, concerns about pressure drop and insufficient flow capacity. But it also puts a limit on the efficiency of our hot water delivery system.

Seeing that a built 3/8 inch twig line didn’t cause the world to implode was rather exciting. Not only that, but the 3/8 inch cold water line services three fixtures: 1) the toilet, 2) a sink, and 3) a shower, while the ? inch hot water line only serviced the sink and the shower.

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The structured plumbing system that I have described in a previous post, recommends the use of 3/8 inch twigs. But each twig should just service a single plumbing fixture, not multiple fixtures.


Serving three fixtures with cold water and two fixtures with hot water using a 3/8 inch twig lines would take us – so one could argue – into deep water. That begs the question: Why would several fixtures on one twig be acceptable?

The bathroom in the Swedish single family home is meant to be used by a single person at a time. In other words, you shouldn’t need to worry about somebody flushing the toilet or using the sink while you take a shower.

And I used that shower. There was no problem with the water flow rate or the water pressure, despite the nine feet long 3/8 inch twig. And being the nerd I am, I let the shower run while flushing the toilet or turning on the sink faucet. There was a very brief but minor pulse in the shower’s water flow, but other than that, no detectable flow reduction or pressure loss.

For full disclosure, I should mention that the bathroom in question was on the 1st floor and only a few feet away from the water heater and water main. The second floor bathroom has a different set up. Here a 1/2 inch twigs (or branches) services the various plumbing fixtures, probably to mitigate pressure loss that may come with the elevation and friction that comes with the longer pipe run.

Now – is that 3/8 inch twig I observed an exception? Apparently not. I noticed almost the exact same setup in a restaurant men’s room — a 3/8 inch twig servicing all fixtures.

As unscientific and nerdy as this is, I am delighted to see proof that 3/8 inch twigs can work and can be safe. But to whom can I take my “I told you so?”

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Has the cabin fever set in by now? If so, let me lead a quick expedition into the hot and muggy summer months. Even though we may yearn for summer heat at this time of the year, once it is upon us, we are rapidly looking for ways to keep cool. How do you keep cool?

I dislike the typical excessive air conditioning we exercise, but I am a big fan of ceiling fans.

You could argue that any ceiling fan would do a good job as it is most likely to operate more efficiently than a conventional air conditioning system. This comparison is somewhat unfair as the product of air conditioning is different from that of a ceiling fan. But then again, humanity is famous for buying products that are non-essential.

We needed to make a decision about what ceiling fans we should acquire for our deep energy retrofit. I started by looking at the extremes. On one end there is the $25 product, cheap but flimsy, “delightfully” humming along while it moves air (for all those lovers of white noise), and dumping the one thing from the motor and light that we want the least – heat.

On the opposite spectrum is … well, other than expensive, I don’t really know. This is a good time to consult the EnergyStar product list for ceiling fans.


EnergyStar rates the efficiency of ceiling fans by how much air they move (cubic feet per minute or cfm) with one watt of energy. If you download the list of certified ceiling fans in Excel format, you can easily sort for the most efficient EnergyStar certified models. Here is a summary of the top three contenders as of February 2014:


There are plenty of other efficient ceiling fans on the EnergyStar list. But after my big time-waste tracking down an EnergyStar efficient range hood, I acquired an attitude. If I can’t find a product listed on the EnergyStar list in a simple online search, I move on.

Back to the top three contenders that were all easy to track down. The Haiku and MidwayECO are built with the efficient and very quiet electronically commutated motors (ECM’s). I assume that the Aeratron is also powered by an ECM, but couldn’t find corroborating information in the specifications.

The Aeratron is a ceiling fan unit only, while the Haiku can be fitted with a 1,500 lumen LED light module. The Midway ECO comes with a light module that takes four LED or CFL bulbs with the GU24 pin base. Tthe typical light output would be around 3,600 lumens. The Haiku can be dimmed as can the Midway ECO, as long as dimmable LED or CFL’s are used.

Prices for the models vary widely as of February 2014:

  • Haiku from $825 to $920
  • Midway ECO from $476 to $529
  • Aeratron from $224 to $349

Because we need dual functionality from our ceiling fans (air movement and light), the Midway ECO emerged as the best contender, even though it is still a very pricey piece of equipment.

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Price check, and – surprise!

I needed more rock wool insulation – a whole lot more. It’s for the second floor exterior walls and the attic.

My primary rock wool supplier, the Chicago Green Depot, went out of business about a year ago. I needed to find a new supplier!

Back in the day, the Chicago Green Depot had the best priced rock wool. I got the last batch in early 2012 for around $35.00 per bundle (60 square feet of 3 1/2 inch rock wool batts). All other sources I contacted, including your typical big box home improvements stores, always came in more expensive.

This time around, April 2013, didn’t seem to be any different. The Home Depot had the bundle of rock wool listed for around $43.00! I thought, though, that it couldn’t hurt to double check the pricing for 120 bundles at the Pro-Desk in my local store.

The printout I was handed listed a total of $3,340.80. That breaks down into a unit price of $27.84 per bundle plus tax (or $0.13 per board foot). That is a considerable price drop from the listed $43.00 … around 35%! This is even less that the first batch I bought for the basement installation.

Do I need to say that I was a very happy camper?

Why that 35% price drop? If I go to the Home Depot and place an order over $2,500, I am referred to – what they call – the bid room. Because I am buying in bulk, I have access to a different pricing structure. That said, I would be surprised if that 35% discount will last for long; this may be part of a current promotion.

The significance is that this is the first time that I bought a substantial amount of building materials from a typical big box home improvement store. Materials for a deep energy retrofit like ours were in the past not available, hard to get special orders, and/or too expensive.

Is this a sign that green building materials are on their way into the mainstream?

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Summer heat or summer freeze?

With the summer heat and humidity upon us, it is nice to escape every now and then the mugginess and soaring temperatures. Escape into a slightly cooler space, except that those spaces are impossible to find.

I think this is a recurring summer topic. Last year, I wrote that instead of cooling off some, we are sent into a deep freeze. I dread stepping into and out of any grocery store, which usually has been turned into one giant freezer. Going to the movie theater requires extra warm clothing in order to avoid hypothermia. The first thing we do when stepping into a restaurant or bar is scoping out the location of the air vents in order to find a seat that is outside the reach of the freezing draft.

I wrote about the industry standard for air conditioning including the recommended temperature ranges, and contemplated the need for a more adaptive approach. An approach that sets indoor temperatures somewhat proportional to outdoor temperatures, making the transition from the outdoors to the indoors much more pleasant, and less like a temperature shock.

The constant transition from the outdoor 90’s into the conditioned mid to lower 70’s cannot be good for our physiology. Or is it? Well, that’s what Google is for.

I searched for negative health effects associated with air conditioning or excessive air conditioning, and found … nothing!

All I found were references to excessive heat and associated health risks; or the spread of bacteria and mold spores through AC systems or reported cases where Legionnaire’s disease has been spread from cooling towers. But nothing really on the effect on our physiology.

I tried something else: I Googled the same subject in German. Et Voila, (pardon my French) I stumbled on a couple of references to sources that discussed the issue of temperature differentials between air conditioned spaces and the outdoors, and associated health issues.

One recommendation that showed up a couple of times, was to restrict the differential to 10 degree Fahrenheit. Admittedly, this has to be set into the context of central Europe, which doesn’t all that often match our Midwestern summer temperatures.

The German web references also mention that the transition across a broad temperature differential makes our circulatory system work extra hard. On reference compares it to a sauna experience, except that in the case of the sauna the cooling down time is relatively short, followed by a resting time in a normal temperature environment. Plus the cycles from hot to cold during a sauna experience are typically limited to two or four times.

Running a number of errands during a hot summer day can in fact exert more stress on our physiology and circulatory system than a typical sauna visit.

Now, why is it that this is not discussed in the English language? Or is it just me, doing a lousy job on Google? Have you come across serious articles and publications that address this topic? If so, I really would like to know about it! Please leave a comment.


1st floor ventilation fittings

The last post concluded with a few thoughts on material choices. Maybe I should start this post on the same subject – materials – but with a focus on duct fittings and accessories.

I was surprised how hard it was to track down some of them. The items that caused me real difficulty were the eight inch diameter butterfly dampers, an eight inch diameter wall hood and an eight inch diameter roof cone.

For a while, I thought I was looking in the wrong places. But after having contacted a whole slew of HVAC suppliers, I still had no luck. After hours of research I ended up buying what I needed from a variety of specialized suppliers.

Wouldn’t you think that these are more commonplace? Apparently not.