Posted to AirparkHome-Remodel by Ross in Hillsboro, OR
on 9/6/2009 4:29:22 PM
I'm wanting to order a final "rough-in" inspection on the electrical work in our shop space. This space will not be demoed as part of our tear-down remodel. However, the mechanical for the heat will be in this space... so I really need to settle on a boiler solution for the hydronic heat. We don't have natural gas where we live, and from all the talking I've done with neighbors, propane is expensive.
The propane company will set me up with a "rental" tank and piping to the side of the house for about $160. So I could go with propane, but at the moment we are leaning towards an all-electric hydronic boiler. One of the HVAC contractors I spoke to talked about a hydronic heat pump and geothermal, but the initial costs for these units is greater... plus, there is zero information for the DIY'er on an air-to-water heat pump. Seems to me there is a market for this.
In my quest to figure stuff out for myself, I came across a book on hydronic heat and bought a used copy from Amazon, the book is: Modern Hydronic Heating, for Residential and Light Commercial Buildings it is written by John Siegenthaler, P.E. P.E. means "Professional Engineer" which means he did lots of studying, and passed at least one state test to be a licensed "engineer", and I believe he can sign off on his own building permits... but I digress (again).
At any rate, this book has the calculations for the jump to light speed in it, so you can get to Alderaan, or if like me you need to figure out how big your boiler needs to be, you can calculate roughly what the heat loss of your house will be and size the BTU/KW of your boiler. Somewhere, I have sheets and sheets and a spreadsheet of these calculations, and can't find them... but I believe I came up with 26-28kW or around 96,000 BTU. (The conversion between BTU/kW is in this book somewhere.)
There is also a reference to "degree heating days" and some other stuff that isn't really well covered in the book, but I dredged through the Web. I wish I had kept better notes, as there are not too many good websites with the degree-cooling day numbers you need, and it seems this is all designed to force you to be a member of some society of HVAC professionals so you can get the book with the secret sauce for your area in a table. I did find it once, but remember having a hard time to find it again. You need that number to figure what your "average" and peak heat losses are. All this was a great way to spend my time when I didn't have any $ to do anything else. Certainly, if you hate algebra, you can avoid this book. I did find that my 26-28kW was about the same as one of the bids for a boiler, so I figure I must have stumbled on the right answer. (My other bids didn't specify boiler size.)
From that, I have found the following electrical boilers:
These boilers are all (I believe) "modulating" boilers, this means they have the electronics to "modulate" the current (basically switch off/and on current quickly), this reduces the amount of heat generated when the "full on" heat is not really needed. The nice thing about this is that it really isn't as important to worry about going "too large" with a boiler as it was in the past, as the modulating feature of the boiler will save energy that would otherwise be lost if you as a "DIY'er" choose too large a boiler. That's not to say that having a HVAC engineer do all the calculations isn't worth the $80/$100 an hour... but I'm not too sure most HVAC contractors really have your particular house designed by a $80/$100 Professional Engineer who has done heat load calculations on your house anyway. I could be wrong, I mean the one HVAC company I talked with certainly knew what they were doing, but they weren't going to give me any "free" specs on my project, which is fair enough.
At the moment, the electro-boiler is looking pretty good, but the SEISCO wins hands down on having THE BEST web resources and suppliers for selling direct to DIY'er's. I would say they are my number-one supplier, but there were some negative customer comments on a couple of blogs, so instead of selecting them hands down, I have been doing this additional research to see who else is out there, and what the damage would be if SEISCO turned out to be a poor choice and I had to redesign the mechanical room for the $1,000 more expensive boiler. If money was no object, I would go with a geothermal unit or the heat pump, and use the contractor who I discussed it with. They do many "large" custom homes for Portland Trailblazer players, and other wealthy clients, and it's clear they have been in the business and have done hydronic heat a long time. I'd love to be able to select them. In the meantime, a $1,400 SEISCO slapped on the wall of the shop could very well heat my entire house for a time until I can afford to upgrade. If I use quality manifolds, and lay out the zones properly, I think I can save $$$$. We shall see... this is just a blog post of an idea at this point.
Back to the electrical, for these "point of use" water heaters, and electric boilers you need THICK copper cables and lots of them. The SEISCO requires FOUR separate 40A double (range type) breakers to feed it. If you have 200A service, make sure the electrical code in your area accept this as an "intermittent" load. If not, you just used up 160A of your 200A to heat your home. In my case I have 320A service, so I've got 2EA 200A panels to play with, just in case the county decides to treat the load differently.
Most of the other electrical water boilers require up to 3EA 60A double (range-type) breakers, so plan your water heater close to your electrical panel to save on copper wire.
|Electrical for the electric boiler will go "somewhere" on this wall. Need to figure this out before calling for a rough-in inspection as I want all the wires placed (if possible) beforehand.|