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Redneck Radiant heat…

Dagwood | Posted in Energy, Heating & Insulation on July 5, 2004 05:31am

MY GF and I are both in college, and for the last two years we have been trying to find a way to put heat in our house that is both affordable and will work.

The house – uninsulated, clapboard exterior, built in 1933 with “Wonderful airflow” (Drafty) – is in Southern Ontario, Canada. We have gotten a routine in place to deice the bathroom on winter mornings. We have 400 sq feet (its tiny) to heat and no budget whatsoever to work with.

In the paper this weekend a boiler was for sale – $250 for a 160,000 BTU unit. We bought it, and then came across two of the old, heavy cast Iron rads and a pump at a garage sale. Another $300, and we think we may have a workable heat system.

Since our house has no accessible crawlspace, we are going to have to run our piping for the system with a fish tape, and we aren’t suer what all to expect in the process. I am hoping some of you pros can offer a little advice. Here is what I envision…

THe boiler previously ran 5000 sq ft of in-floor radiant heat for a carwash. The guy who had it was running 1″ PEX tubing off it, the rads were run off a smaller boiler with 3/4″ copper line. I am thinking I will run 1″ PEX to the rads, and then adapt to copper to go into them.  The shutoff’s for the rads will be copper. Does this make sense? Also, is there a good way to fish PEX tubing?? I can’t imagine a fishtape working well for this, and the ground under the house is very uneven. I have heard of people using a RC car to run a line, is this what I should be thinking??

Any advice is appreciated. If this is bigger than I should be attempting, please say so! I will be having everything inspected once its in place.

Thanks,

DAGWOOD

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  1. Sasquatch | Jul 05, 2004 06:35pm | #1

    Normally, HVAC systems should be sized to the application.  I am guessing that your ten times oversized system will not be efficient and will cost you a fortune to run.  Unless you can guarantee that your system will never go down in freezing weather, I would be careful about running PEX in the crawl space.  If you can't get in there to run the tubing, it will be even more difficult to make a repair.  I would call in a professional on this one.  Good luck.

    Les Barrett Quality Construction
  2. DanT | Jul 06, 2004 02:46am | #2

    I don't know how it is in Canada but in my area you can almost always find a working used forced air furnace for sale for $1-400.  With only 400 SF why not buy one, stick it in a corner and put a plenum with a few elbows off it pointed in the direction you need heat.  Simple, wouldn't have the money you have already spent in it and you could turn the heat up and down based on occupancy unlike the system you are considering.  Hot water heat takes a considerable amount of time to raise the tempature in a room where as forced air it can be done quickly.  DanT

    1. Dagwood | Jul 06, 2004 03:47pm | #4

      Thanks Dan.

      Forced Air Gas is impractical in the house. I have tried to figure out a way to run it, but without banging some big holes in bad places, I don't think it would go. Since what basement we have is only 5 ft high and wide, the size of the furnace would also be an issue.

      The biggest difficulty with Forced Air is that the house has a concrete wall running under it the width of the house, and putting the plenum through it would be more of a challenge than I am up to. I am hoping that running water lines will be easier.

      The people I have talked to about heating the place have all suggested either in-floor radiant heat or wall-mounted gas furnaces to replace what I already have (I posted on here earlier about Rinnai Furnaces). It would take two wall mounted units to heat the house and at $2400 each I have no stomach for that.

      I will look into used furnaces in the area. I may be wrong in my size and adaptability guesses for the furnaces.

      Thanks Again,

      DAGWOODView Image

  3. davidmeiland | Jul 06, 2004 03:21am | #3

    I think you should spend your money on insulation and a couple of electric heaters, but you could make something out of the radiant system if you're willing to spend a bunch more money and do a whole lot of work. Here's an overview of what a radiant installer would probably tell you to discourage you from trying this.

    First, you need to civilize the crawl space. No way you want to just snake pex down thru there sight unseen. Plus, you're going to need to insulate any piping in unconditioned space. So, chase out the spiders and raccoons and do some tunneling if you have to, but get access.

    Figure out where the boiler is going to live. Once you do that you need to pipe in the gas supply (perform a proper pressure test on the piping before connecting appliances) and build a flue, probably out of double wall (b-vent). Also connect a pressure relief valve and pipe that outdoors per code.

    Next you need a boiler board. At a minimum that will have a control (probably a Taco) that will recognize a call from the thermostat to fire the boiler and turn on the circulator. The control should cut off the boiler if the return water is above a certain threshold. You need a makeup water line coming in thru a pressure reducer and a strainer with a pressure relief. You need an expansion tank because you're building a closed system. You need a purge valve for bleeding air from the system.

    You can either run the rads in series or in parallel from a manifold. A manifold is more flexible, so buy a pair (one each supply and return). I suppose you could run the lines to and from the rads in pex, but it's more typical in my experience to use copper for that. The near-boiler piping is definitely copper.

    You will probably find that this project is more than you can do easily, and it may not really make the house comfortable because it isn't insulated. It may not even work unless you get a radiant pro to lay it out for you and specify all the particulars. It will definitely cost a lot to run.

    1. Dagwood | Jul 06, 2004 04:12pm | #5

      THe boiler I bought has a built-in thermostat, it automatically fires a piezzo ignitor to heat the water when it cools beyond a certain point (The boiler is from AO Smith). I had not considered the need for a pressure tank, but will look into that.

      A number of people have commented that this system will be expensive to run, but I can't understand why. If the boiler heats the water to a temperature set on the thermostat, what difference does it make what the BTU output/input of the boiler is as long as I have the thermostat set to a given value? Or is this like saying whether I drive a honda civic or a mac truck to get to the store I can still get my groceries?

      We HAve been trying to insulate the house since we moved in. And so far we have 2 exterior walls done. It hasn't been an easy task, and we are finding the cost of insulating is lost money. The exterior walls of the house are Cedar clapboards, so an air gap has to be left between the boards and the insulation. In order to insulate we have to remove the Lathe and plaster from the interior of the walls, line the stud bays with rosin paper, put in insulation, seal the inside of the walls with vapour barrier, then drywall and paint. I am sure most of the folks on here could do the house in a weekend, but on a student's budget, the rebuild goes slowly, and materials are hard come by. In another 2 years I will be moving out of this place, and I would rather not trouble myself with the cost of insulating the whole thing. Real estate has advised me to tear down the house when I sell and sell the property as a lot.

      By civilize the crawl space I am guessing you mean bust a hole through the foundation, and make a working space where I can run the Tubing and strap it to the underside of the floors?? That may be do-able as there is a spot along one side of the house where (this sounds bad) a chunk of the foundation fell away. If I can open that up a little more I may be able to squeeze in under the house and make a working space.

      The boiler will sit in a corner of the basement, it will be under the kitrchen where there is already a stubbed out gas line . It is a branch off the gas service that presently has the kitchen stove on it. I am thinking I can put a Tee on that line, and run a length of black pipe to the boiler. Also since it is under the kitchen I can run a tee into the water line to the Kitchen sink to have a supply line for the boiler (Is the supply supposed to be hot or cold water??)

      The guy who is selling us the boiler will include the venting with it, enough to get us to the roofline. THere we have to switch venting type, and we will have to buy that and the cap ourselves. I understand that buying venting can be pricey.

      There is a pressure relief on each of the rads we got... I am guessing you are right though we will need a bleed and a pressure relief at the boiler (Hadn't thought of that either).

      I am not sure what a boiler board is. The boiler has a thermostat built into it, and I thought the pump ran constantly. Can't I just control the heat of the water at the boiler and it will cycle on and off automatically?

      As I type this I am beginning to think I will run the piping and supply lines myself, and put in the gas lines, but have a pro set up the boiler, pressure tank etc. My greatest fear is in screwing up the venting and gassing myself.

      Thanks for taking the time to reply,

      DAGWOODView Image

      1. DanT | Jul 07, 2004 12:05am | #8

        Why not just insulate with blown in cellulose?  You can rent a blower.  I have never insulated a house that  took more than $350 in material and they were all a lot bigger than 400sf.  DanT

  4. frederic | Jul 06, 2004 09:46pm | #6

    I am currently reading the book as suggested from someone here at breaktime called "Hydronic Radiant Heating, A practical guide for the Nonengineer Installer" and the author mentioned that the house really needs to be well insulated.  It makes sense because if the house is as drafty as you spec you will probably not be able to space or size the tubing sufficiently to heat the room to compensate for excessive losses.  The other issue was with oversized boilers, It is better to have a smaller sized boiler start up and run for a longer period of time than one that starts, reaches it desired temps. then shuts down frequently because you waste energy on the start up operation as oposed to using the enery to heat the water.

  5. csnow | Jul 06, 2004 10:36pm | #7

    That boiler is completely oversized for 400 SF.  160KBTUs would be good for something on the order of a 3000 SF home with poor heatloss characteristics.  It would short cycle so badly, that it would never run right.  Plus, the components and piping scheme to get it going is more complicated than you are imagining.  You might be a good candidate for a heating system running off a hot water heater instead of a boiler.



    Edited 7/6/2004 3:41 pm ET by csnow

  6. User avater
    Luka | Jul 07, 2004 01:11am | #9

    Insulate with bubblewrap. Or styrofoam peanuts. Or anything else of the sort that you can get your hands on. Later, when you can afford it, replace it with the real thing. Bit by bit, if you have to. Bit by bit still gets you there eventually, and it is not as depressing as just sitting there doing nothing because you can't afford to do it right the first time.

    Get yourself a small lopi woodstove. And two honeywell baseboard type heaters. The woodstove will save your electric bill by running when you are there. The electric will keep you warm when the fire dies at night. And will keep the place from freezing while you are away.

    One thing you can do right now that would be very inexpensive, but would be labor intensive... Pull off the clapboard, and put two layers of tarpaper under it, then put it back up. If you don't care about the looks, just wrap everything in the tarpaper for now, and side when you can afford it.

    Put on layer on as usual, with at least 6 inch overlaps, shingle style. Put the next layer on by starting with a half-high run. That should make all the second runs overlap at the middle of each of the first runs.

    400sq ft can almost be heated by buying a large supply of bean burrito's and lighting off your farts.

    I have one other suggestion that hasn't been made yet...

    The newer furnaces for RV's. These things are very efficient. You can have a thermostat on the wall. The fire gets it's combustion air from outside, and all combustion air is vented back outside. No huge vent stack needed. What is in the box, in the house, is all sealed.

    Set a propane tank outside, and run one line through the wall to the furnace.

    I guarantee a couple of these will heat your space, and do so fairly cheaply. Granted, my space is less than 200 sq ft, but in the worst winter we have had here... For the single worst month... I kept my place at 70 all the time, and it cost less than 100 dollars for the propane.

    You can use any propane tank you want. In time, get a really big one, and have it refilled if you'd like. But for now, 4 or 5 ten gallon tanks can be refilled at your cheapest supplier, and easily carried by you to location.

    ALWAYS fill the other three tanks immediately when you hook up the last one. You'll want that woodstove anyway, for when you are snowed in, no power, etc.

    The rv furnace can usually be run on a car battery if need be. Deep cycle are best. And if you are going to rely on it for backup, you should have it always on one of those maintenance chargers. If your power can be off for longer than just a few hours, get a couple of golf cart batteries instead. Wire them up so you have 12v instead of the 6 apiece from the batteries. These things hold a charge longer than any other normally available batteries. They provide power for longer. And... they have a very long overall life. I heard something like 4 times as long as a marine deep cycle battery ???

    Who cares, wins.

    1. jjwalters | Jul 07, 2004 11:39am | #10

      Luka has given you good advice.............you can also buy a propane free standing (fake log) stove that's pretty and puts out a lot of btu's. .......You're gonna make yourself crazy with the radiant idea. 400 ft is NOT that hard to heat.......simply.  

    2. Dagwood | Jul 07, 2004 04:26pm | #11

      Thanks for the Ideas Luka. Will look into the cost of bean burritos and Lighters (Would you reccomend bic, or will those dollar store ones work ok??)

      Seriously though, you have offered some Idea I hadn't even considered (propane, RV units).  I don't think anyone around here uses propane for heat - its all Natural Gas or Oil. We had looked into a NG woodstove, and it took up too much room with the clearances etc. that the guy needed on the stove he reccomended. When we suggested 0 Clearance he had some reason for it not being what we needed. I forget why now, that was before winter set in last year.

      I hadn't bothered calling anyone in to blow in insulation since I thought rotting walls were a concern. If I had someone blow in the stuff, how long would I have to redo it right? Honestly with how much school work I have right now I don't have the time to take down the claps and redo the tar paper etc.

      Thanks again,

      DAGWOOD

       

      View Image

      Edited 7/7/2004 9:49 am ET by DagwoodBumstead

      Edited 7/7/2004 9:50 am ET by DagwoodBumstead

  7. JRuss | Jul 07, 2004 04:39pm | #12

    You can follow all of this great technical advice, as for me, if I were you, I'd make better use out of the GF.

    Never serious, but always right.
    1. Dagwood | Jul 07, 2004 04:55pm | #13

      Here is the house - just to give you an idea of what we're looking at. The white section has been insulated - the rest is not.View Image

  8. DanH | Jul 08, 2004 01:36am | #14

    You might be better off running the pipe through the attic. In any event, it might be a good idea to use pieces of lightweight drain pipe for "conduit" -- this will provide support and rodent protection for the PEX and a modicum of insulation. If you do decide to work in the crawl, you'd just need to work one large piece of drain pipe (like 6-8") into the space from the boiler down to the last rad, then you could snake your pipes through that. You could also snake a cable heater in there for backup protection against freezing.

    You might also consider routing the pipes inside the house, along the corner of the ceiling or some such. Frankly, it's not clear that they would detract that much from the decor.

    For fishing stuff in a space like your crawlspace the best tool is usually a long pole. Fish a rope in first, and then use that to pull the PEX through.

    In a slightly larger space a weight you can throw is often the best choice, but you probably don't have the room for that.

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