Tag Archives: Water Heater

Core Plumbing is Done!

24 Wednesday Oct 2012

Posted by in Arduino, Home Improvement

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Core Plumbing

I’ve finally gotten enough done on our core plumbing that I’m willing to post a photo.  This has been my baby for a few months and I’m obsessed with every detail.  As with most of the other projects, we’re aiming to save as much space as possible. We have reduced our entire heating, hot water, gas and water distribution systems from a furnace, water heater, ducting, and associated plumbing into a 4′ wide x 5′ tall x 1′ deep corner.  This transforms a basement only fit for storage into one fit for a workshop.  We’ve gained a full floor on our house.

Here is how the system works:

Water enters from the city via a 3/4″ copper pipe (lower left) through a code required back-flow preventer and expansion tank into our 1″ radiant floor manifold.  From there 3 pumps send water to each of our 3 floors (once we hook up the PEX you see in the top right), back to the lower manifold, through the tankless [high-efficiency condensing] water heater, through a 1 way valve and back around again.

This design uses manifolds made by Radiantec and is laid out based on their reference design.  I’ve made a few slight changes to save space, but keep everything oriented as they suggest.  They key was layering everything in planes.  I planned this out in Sketchup which really helped to visualize different layouts before I even had the parts in hand.

We get hot water out of the system for the house from just after the water heater and before the heating circuit’s one way valve.  Hot water that is removed is replaced by water from the water main.  Cold water for the house comes from different parts of the system depending on the position of a manual diverter valve. When we are heating the floors, the valve pulls cold water from the main before it gets to the heating circuit.  When we are not heating the floors, cold water has to go through all of the floors before being taken out before the water heater.  In addition to preventing stagnation during the summer, this is supposed to supplement our cooling by removing a few BTUs of heat via the floors as we use water.  Summer heat literally goes down the drain.  The downside of this is that our “cold” water will now be room temperature.  Since I dont like drinking warm water, we’re going to tap into the main just after the back-flow preventer for nice cold drinking water which we will run through filter to remove the city water taste.

Due to the efficiency of the water heater and its low exhaust gas temperatures we are able to use PVC pipe for the intake and exhaust (top).  This is going to be run across the ceiling and out the side wall into the alley.  The run is short enough and has so few bends that we can get away with running 3″ PVC.

The electricity has not yet been run around the basement.  We will need around 1 amp for each pump and an amp for the water heater itself.  We’ve decided to try and build our own thermostat based on an Arduino microcontroller.  Input will be temperature sensors in the floors of each room (Dallas DS18B20) and output will be solid state relays which can supply up to 2 amps per circuit.  I’ve come up with a simple algorithm that turns the pumps on if the temperature is below a set point (and off when they reach the set point + hysteresis).   The hard part is the interface.  We have an Arduino Ethernet shield which allows us to connect to the controller via our network (and the Internet).  I’m hoping to make apps for our phones that allow us to set the temperature and check the status of the house from anywhere with a wifi connection.  Data logging is also a goal.  This is going to take a little while to implement so for now we’ll set the temperature with a laptop via USB.

Lets Get Mechanical!

09 Thursday Aug 2012

Posted by in Home Improvement

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This has been an expensive week, but in a good way.  We’ve ordered and received our radiant floor heating system.  This is something we’ve been excited about since we first looked at the house.  The house had a set of problems consisting of the following:

  • Drop Ceilings – Ugly and had to go.
  • Galvanized Piping – Old and prone to corrosion
  • Water Heater – 20 years old and dead.
  • Furnace – 50 years old and dead.
  • Ducting – An utter mess.  One of our chimney’s was used to hold both an exhaust pipe and serve as a heat duct.

We feel the Open Direct System by Radiantec was the best solution for this particular set of problems.

The Open Direct System uses the same domestic hot water heater that makes hot water for bathing and laundry to provide space heating, too. Everything in the system is made of materials that are fit to drink from, and a plumbing detail prevents stagnation of the water in heat tubes during the summer when space heating is not required. For details of this system, see Open Direct System or see page 23 of the Installation Manual. By reason of its efficiency, cost, and simplicity, this is our preferred system.

While we have the ceilings open, we can install the PEX tubing and insulation under the floors.  We can also replace our galvanized piping in the basement as we reroute everything for the new system.  By removing the old water heater and furnace with a single small wall mounted heater, we clear tons of floor space.  We will not need ducting nor a chimney either.  Heat is delivered in runs of 5/8″ PEX tubing and exhaust can vent through the wall via PVC pipe.  With all this new found room in the basement I might have room for my secret laboratory!

I recommend reading through the Radiantec website for more info.  It has a ton of articles about how this system works, potability, stagnation prevention, code compliance, and cost.

Heating needs as calculated by Radiantec

Part of going with Radiantec was to get them to spec out what we would need for our particular house.  With under 1000 sq ft of heated space, heat requirements were low enough to substitute a cheaper Noritz [NV98-CV-NG] tankless condensing gas water heater rather than the more expensive Polaris and a MUCH more expensive boiler.  This not only saves us money, but saves us floor space in our already tiny house.  At 92% efficiency, I hope it will also keep our heating and hot water costs low.  If not, we should be able to add solar water heating down the road.

While we went with their whole system for heating, we opted out of the thermostats supplied by Radiantec (for now) while I explore using an Arduino micro controller to control our heating and eventual air-conditioning systems.  This is really nerdy stuff, but I’ve been waiting for a system control project to come up where I could play with it.  I’ve ordered an Arduino Uno, Ethernet Shield, 10x DS18B20 temperature sensors, and an 8 channel solid state relay board (2A @ 120V / channel).  The plan is to build a system that we can access by apps on our phones, or via a website that can also datalog our energy usage.  If this doesn’t work, I eat the cost and we buy the Radiantec controls.  I’m sure there is something fun I can do with an Arduino if this doesn’t work.

We’re so excited to start installing this stuff over the next few weeks.  Really looking forward to warm toasty bare feet this winter too.