Major DIY home renovation in the future-thinking of converting to hot water heat


Old 08-01-11, 04:07 PM
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Major DIY home renovation in the future-thinking of converting to hot water heat

My wife and I bought our 700 SF single story 2 bedroom/1 bathroom ranch with attached garage in Northwestern NJ a little over three years ago. We just finished the basement which gave us an extra 400 SF of living space in the form of a family room, but we'll need more room soon. We knew we would either have to add on or move one day since we are hoping to have three children (our first is due this September ) eventually, so with the housing market being what it is, I think it would be wise to plan for an addition in the next 4-5 years. Basically we need one more full bath and one more bedroom for a total of three bedrooms and two full baths. The addition I've sketched out will simply be a 15' x 26' box tacked onto the rear of our existing home. This will provide the space for two new bedrooms. One of the existing bedrooms will be divided into space for a hallway to access the two new bedrooms, and a full bath connected to the master bedroom. I've been fooling around with ideas in Google Sketchup (amazing tool considering it's a free download) and made up a graphic to illustrate the existing house vs. the planned addition-with it we'll top out at just under 1400 SF:

The blue walls are the existing walls of the home so you can pretty much tell what the original building envelope looks like. The pink walls represent the planned new construction. The grey walls represent the present bedroom which will be cut up into a hallway and a master bathroom. I realize this isn't a DIY construction site, but I figured that some background would be helpful. Right now the home has a 6 year old forced air oil furnace which we supplement with an add-on wood furnace which is integrated into the existing ductwork. We like heating with wood, and provide most of our heat this way, burning five cords or so per winter, but we hate the forced air heat. There are lots of cold spots in the house no matter what we do, and the dryness is just awful in the dead of winter, plus my wife has bad allergies. In any event, we want to be rid of it when we renovate. I will be doing a lot of the work myself-my FIL is in the construction industry and will be serving as my adviser for the entire project. He will get me subs for the excavation, foundation (there will be a full basement under the addition), and electrical, but the rest we'll be doing ourselves/with the help of a few laborers. Basically I'm trying to get an idea of what skills, tools, etc...I need to install an oil boiler myself.

First, obviously I'm starting from scratch as there is no existing infrastructure for hot water heat. Part of what always made me leery of hot water heat was sweating copper and working with rigid pipe in general. Despite a lot of DIY experience this was something I never quite mastered. Lately though I've been reading a lot about PEX and it's applications in hot water heating. I also happened to see an episode of "Ask This Old House" where they used PEX to add a zone to an existing hot water heat system and it looked fairly straightforward. Is installing a boiler these days really as easy as running attaching PEX to each zone valve, snaking it up to the appropriate baseboard, and then doing the same to bring it back to the cold side of the boiler? I'm hoping so since working with flexible PEX would be a lot easier than cutting copper pipe, sweating elbows, etc... I know I'll still have to do adapters, which is fine-should be easier than trying to do in-place copper tubing in some cramped part of the house. I have the basic idea of how a hydronic system works down, but one thing I know nothing about is sizing baseboards for a room-can anyone tell me what a good installation would look like in house like mine? I know that I need to do a heat loss calculation to size the boiler, but I have no idea how much baseboard an 11 x 14 bedroom or an 8 x 11 bathroom needs. What about zoning? Our house is not that big and it seems to me that it could all be on one zone-two if I decide to heat the garage-does that sound right?

Finally, this is all going to part of a larger system. I want to stay heating with wood, so essentially I'll be buying two boilers-a small oil boiler that will be used occasionally (when we're not home for days at a time or if wood is scarce-which is not often), and a wood gasification boiler which will provide heat 90% of the time. The two boilers will be piped in parallel. I was thinking of something along these lines for the oil boiler:

I don't want to spend the money for a high efficiency unit when I'm only going to firing it once in a while at best. Since I installed my wood furnace two years ago I've only filled the 275 gallon oil tank twice! My neighbor filled his three times just last winter-same size house, and his was a lot colder than mine. Any, just looking for feedback on sort of run-of-the-mill-not-terribly-efficient-or expensive oil boilers. During the renovation I'm going to tear off the old siding and install housewrap, airseal, sheath with 4" of rigid foam, and cover with Hardi-Plank. That should give me a good R-30 wall. The attic will be airsealed and loaded with cellulose on top of the meager six inches of fiberglass for an R-60 rating. If I did my heat loss calc correctly the above boiler at 100K BTU should do the job just fine. I'm eager to hear from anyone else who has taken this plunge.
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Old 08-01-11, 06:03 PM
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Can you boil your post down to a simple question?
Old 08-01-11, 06:48 PM
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Originally Posted by gilmorrie View Post
Can you boil your post down to a simple question?
Sorry for the textual diarrhea Basically I'm interested in hearing from folks who have installed their own boiler/hydronic heating system and about all of the potential pitfalls, wouldas, couldas, and shouldas.
Old 08-02-11, 11:28 AM
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hi IH Ė

Sorry Iím a newbie and have no expertise. But IMHO I donít think you should let sweating copper sway you one way or the other. Iím a klutz, but everything Iíve sweated after an initial learning period has been fine and has never leaked. When you say you havenít mastered it I assume maybe you had a leak or two. Maybe you just need to make a minor adjustment in your technique? (e.g., I takes things too literally, and when I read : ď heat, remove the torch when the solder starts to flowĒ, I simply would not put the torch back on to heat the joint a little bit more if needed. Bad results. Then I watched videos.) Plus I think copper has a great track record and will last a long long time!

Anyway, maybe thatís all neither here nor there because maybe all the proís will tell you that PEX , as youíve been contemplating, would be the best choice for you project anyway.

Good luck!

p.s. super diagram.
Old 08-02-11, 11:35 AM
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I have PEX in my house and would use it over copper whenever possible.
Old 08-02-11, 01:36 PM
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Get yourself a copy of Modern Hydronic Heating by John Siegenthaler. All kinds of knowledge for this kind of problem.

DIY installs abound. Some are great and better than 95% of professional work; some on the other hand are simply life-threatening.

The trick is to know your limits and see where you end up on that spectrum. It ain't rocket science. Pay attention to venting, combustion, and have or get the right people with the right tools to ensure safe operation for that which is outside your comfort zone.
Old 08-03-11, 02:21 PM
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thats a neat sketch. i'm gonna have to download that. that would really come in handy when doing heat loss calcs and other things. i would use pex if i were you, but to be honest with you, you could probably cut out atleast 5k worth of material and labor if you stuck with hot air heat. i really can't stand hot air, but I'm starting to see how much money can be saved for new installs. if you have cold spots, perform your load calcs for each room and make sure you are sending the correct amount of air to each room. as far as the dryness goes, get a honeywell true steam humidifier and for the allergies, get a nice 5" pleated filter as well as a UV light. tweaking your hot air system will provide better comfort for you as well as save you a ton of money. good luck
Old 08-03-11, 04:16 PM
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I disagree. Hot water systems are far more comfortable than hot air. I did some calcs on that Truesteam for my home and it is expensive to run.
Old 08-03-11, 06:41 PM
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Converting to hot water? Converting from what? How? This is seldom a good idea. How long do you expect to be in your house?
Old 08-03-11, 08:44 PM
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I know very little of boilers but my boss redid a house a few years ago and removed almost all the rigid pipe and converted it all to PEX. Other then it looking a little sloppy where you can see it (you can't beat a nice copper job) it all works great and no leaks. He also used it for the water lines and again, no leaks.

Only suggestion I can give you is you use the PEX "system" that is available at the home store in your area. That way if you need a fitting it is just a short drive to get one as opposed to buying online.

It looks like you have a good plan there. Carry on!
Old 08-04-11, 06:17 AM
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Be careful buying PEX for heating systems at a 'home store'. Most (if not all) of them will NOT carry the correct PEX tubing for use in heating systems. The tubing you use for a heating system MUST be an OXYGEN BARRIER type of PEX. The standard potable system PEX is definitely not the correct type.

What the guys who are saying to stick with the hot air are saying is that the decision to make the change should be based highly on how long you plan to be in the home. Data shows that HW is less expensive to run... in the long term... than hot air. But the 'payback' on the change over will take more than a few/couple years.

Hot air can be made to work properly, but just as with how water, the system must be properly designed for correct air flow ... both supply AND return air.
Old 08-04-11, 07:06 AM
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You're right on Trooper about the oxy barrier. The effects of using non-barrier tubing won't show up right away, maybe quite a few years, but eventually air vents will start to crud up and then the boiler will start to leak. Had to replace one for that reason and also replaced all the tubing with copper to prevent a rerun.
Old 08-04-11, 12:47 PM
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Trooper is also correct about the cost factor in converting a forced warm air system to forced hot water.

I am quite capable in both hot water and warm air systems (spent thirty years with commercial and industrial boilers and also designed/installed a few residential systems) and when it came time to replace my forced air furnace I determined that it would be at least triple the cost to convert to hot water so I simply (had) installed a high-end furnace. My heat is even throughout the house although there are still a few minor improvements I may make.

That was six years ago and I DO plan on living in this house until I die. The cost factor was simply too much.

Now in your case, since you will be adding on to the original house it may make a great deal of sense to use a hybrid system of radiant floors in the new section and then replace the furnace with an air handler with hot water coil. The cost will still be high but then anytime you add on to an existing house you have high costs.

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