Thursday, December 29, 2016

Hot Water

In an earlier post, I discussed a number of options to provide space heating and cooling.  One of those options was an integrated system that provided both space heating and hot water.  Having not chosen that system, I needed to select a hot water heater.  This choice has several aspects: what fuel to use, storage tank or tankless, whether or not to circulate the water, and whether to include heat recovery.  The criteria include: initial cost, operating cost, and likelihood of running out of hot water.


The realistic choices are electricity or natural gas.  When natural gas is available, oil or propane offer no advantages.  Electric water heaters tend to be cheaper to install but more expensive to operate.  Since natural gas involves combustion, provisions must be made to supply combustion air and to vent the exhaust. The cheapest type to install is an atmospherically vented model.  These draw combustion air from the room and rely on the temperature of the exhaust gas to draw the exhaust up a chimney.  This type is not compatible with a high degree of air sealing.  In a well-sealed house, the kitchen fan or dryer can lower the pressure in the house enough to reverse the flow in the chimney and draw exhaust into the house.  The next step up the expense scale is a power vented water heater.  An electric motor driven fan propels the exhaust products out of the house.   Inside air is still used for combustion.  The most expensive type is a powered direct vent which draws outside air for combustion and sends the exhaust outside.

Storage or Tankless

Storage type water heaters heat a tank full of water up to a setpoint temperature and keeps it hot.  Some heat is continuously lost from the storage tank.  If too many people take showers in a row, the water heater cannot keep up and will eventually deliver cold water.  The usual solution to that is to increase the size, say from 50 gallons to 80 gallons.  Larger units cost more to install and have higher storage losses.

Tankless water heaters, on the other hand, heat the water as it is drawn.  Tankless water heaters must have larger btu/hr capacities in order to keep up with the maximum water flow rate.  Sometimes, that requires upgraded natural gas or electric service from the utility.  They never run out of hot water no matter how many people shower in a row.  Tankless heaters have been known to have trouble regulating the water temperature when the flow rate is low.


When you turn on the hot water, the water that had been sitting in the pipe comes out.  If it has been there awhile, it is cold.  You have to wait for hot water to start flowing.  One solution to this problem is to circulate the hot water so that the hot water pipe is constantly full of hot water.  Of course, that hot water in the pipes is constantly losing heat, increasing how much the water heater needs to do.  This can be alleviated somewhat by only periodically circulating the water, such as when someone turns a light switch on in a bathroom.

Heat Recovery

Drain water heat recovery (DWHR) systems, such as Power-Pipe or GFX, are heat exchangers that recover some of the heat that is left in the drain water.  They are most effective for showering.  The recovered heat pre-heats the cold water entering the water heater and the cold water feed to a shower.  In addition to reducing energy use, these systems increase the number of showers before a storage type water heater runs cold.  These systems are installed in a vertical drain pipe.

My Decision

After much debate, I decided on a 50 gallon GE Geospring heat pump water heater.  This unit uses an electric heat pump to transfer heat from the interior air into the water.  It operates with a coefficient of performance of about 3, meaning that it only uses one watt of electric power for every three watts of heat that goes into the water.  The other two watts come out of the interior air.  In the winter, that increases the natural gas consumption of the furnace.  In the summer, it reduces the electricity use of the air conditioner.  Although it costs much less to operate than a regular electric water heater, it still costs a little more to operate than a gas water heater at current prices.  My major motivation for this choice was to avoid having another combustion appliance in the house.  Some people have complained that heat pump water pumps are noisy and take too long to recover.  I decided that I was willing to take those risks.

Having finally made this decision, I arrived at the house one day and found the plumbing sub-contractor busily installing a power vented natural gas water heater.  I didn't expect water heater installation for several more weeks.  After a few phone calls, things were straightened out.

I decided against any kind of circulation system.  The only fixtures that are very far from the water heater are in the guest bathroom, which I expect will be rarely used.

Although the drain for the master bathroom is suitable for DWHR, drains from the other two showers are not suitable.  (The shower in the basement does not have a vertical section.  The shower in the guest room is used too infrequently to justify DWHR.)  I am pretty sure that the plumbers had never encountered a DWHR system (they had never seen a heat pump water heater).  I decided that this was not the occasion to make the builders do something else completely new to them.  The drain for the master bedroom is in an accessible location in the utility room, so the option remains open if I decide to take it on as a DIY project at some point.

Saturday, December 3, 2016


Shortly after we started construction, Julie and I attended a home show in Novi, MI.  One of the decisions we made there was to install a retractable awning from Marygrove Awnings.  A couple days after we placed the order, they called to schedule installation.  "Sorry," I told them, "you have to wait until we have walls to install it on."  Even after the exterior was almost complete, our builder didn't want it installed too early for fear that it would get damaged during installation of something else.  The awning was finally installed in the middle of October, after we were living in the house.

With 2" of rigid foam on the exterior, I was concerned about having sufficiently firm support.  So, before the siding went on, I decided where each bracket would go and had the framers take out a little section of foam and replace it with solid wood.
The framers, who also did the siding and trim, installed some additional trim in the bracket locations.  (Over the sliding door, there would have been trim there anyway.)  The awning installers needed to get extra long lag bolts that would go through the trim, the siding, the furring strips, the rigid foam, the sheathing, and a proper distance into the studs.
Once five brackets were firmly bolted to the house structure, the crew lifted the awning into place and attached it to the brackets.
The awning plugs into a regular outdoor outlet with a conventional 110V plug.  When the rough electrical was done, we planned for the awning by specifying an outlet in a convenient location.
The finished product in the retracted position.
Given the time of year, we haven't had many opportunities yet to sit on the patio under the awning.  However, we have really enjoyed having it on sunny weekend mornings.  Without the awning, it would be hard to find a spot in the family room that is not in the sun's glare.  We can put the awning out as far as needed to create a comfortable spot to sit and have coffee without impeding our view of any airplanes that come and go.

Thursday, December 1, 2016

Landscaping I - Lawn

We didn't get started on landscaping until after construction was complete and we moved in.  We had hopes that our lawn would soon be green like our neighbors' lawns.  Looking at the calendar, it seems more likely that our lawn won't look like the neighbors' until all of them are white.

The soil on our lot is clay.  After the finish grading and stone removal, several truck loads of topsoil were delivered and spread.
We decided to have underground sprinklers installed right away.  Installing the sprinkler system required running a 1" pipe to the outdoors.  It would have been much easier to do that while doing the rough plumbing.  Once the drywall ceiling was installed in the basement, it was much more difficult.  The fact that we extended the patio further than originally planned made it impossible to simply go straight out from the back of the workshop.  Also, since we have two driveways, it was necessary to bore under one of them.  It would have been much easier if we had buried some plastic tubing before doing the concrete driveway.

This shows the landscape contractor pulling the pipes for the irrigation system with a trencher. 
After the irrigation system was installed, the landscape contractor applied hydro-seed.
The hydro-seed was not applied until a couple days before Halloween.  We had an unusually warm November, but that was not enough for the lawn to come in.  As of early December, there is grass if you look close, but that doesn't count as a lawn.  The contractor says that the seed will go dormant during the winter like grass does and will come in strong next spring.

We get a big puddle at the back of the patio every time it rains.  This takes days to dry up.  Hopefully, once we have grass, the grass will absorb it faster.  If not, I need to come up with some other plan.
In the spring, we plan to put in a handful of small bushes and spread wood chips around most of the perimeter of the house.  We are aiming for low maintenance.