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Thread: Please help me design a new heating system!

  1. #1
    DIY Member Gnfanatic's Avatar
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    Default Please help me design a new heating system!

    Hi guys, I have been lurking around and read quite a few posts here. I am hoping you guys can helpme decide on what to buy. I have a 1600 sq ft house with 2 bedrooms and 1 bath. The bathroom, living room,kitchen and dining room will have radiant heating in cement with tile on top. the bedrooms have cast iron baseboard radiators (made by burnham)). I old oil heating steam system took a dump and I need to replace it. KEYSPAN has a deal that you get a boiler and tank for $899 if you convert. Problem is that the boiler is only 85% effecient. So here are my questions.

    1-) should i get their boiler or pay a little more and get a much more effecient one like a weil-mclain ultra series?

    2-)Do I need a tank?

    3-) I have seen people use 1/2 inch pex, 5/8 or 3/4 for their floors. How do you know what size to use???

    I trully appreciate any suggestions or comments. I only have one income coming in so my budget is around $6000. I already have the rads in the bedrooms.


    thanks!!!!

  2. #2

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    well with only 6K that kinda limits you.
    1)I think you should buy the highest efficiency boiler you can afford. I recomend buderus.
    2) what kinda tank ? an inderect fired hotwater tank is a must
    3) what exactly are you trying to do ? there is a lot more to it then just pick a size also concrete is the worst medium for radiant are you adding this in an addition ? how were the rooms heated before hand ? maybe forego the radiant now and buy a better boiler

    Lou
    Last edited by BigLou; 08-06-2008 at 05:23 PM.

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    DIY Member Gnfanatic's Avatar
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    Thanks for the quick response Lou! I am looking for an effient heating system.

    1)I think you should buy the highest efficiency boiler you can afford. I recomend buderus. I cant get a weil-mclain in my budget>?
    2) what kinda tank ? an inderect fired hotwater tank is a must Def a indirect, I dont know what brand or size.3)

    what exactly are you trying to do ? there is a lot more to it then just pick a size also concrete is the worst medium for radiant are you adding this in an addition ? how were the rooms heated before hand ? maybe forego the radiant now and buy a better boiler. The old system was a steam system, had big rad's in the walls. I took them out and all. I though concrete was greeat becuase the heat in the tubings would heat the concrete. as of now the floors are down to the subfloor in the lvingroom, bathroom and kitchen.


    thanks again!

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    DIY Member edlentz's Avatar
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    I have a radiant system that my wife and I installed ourselves 3 years ago. We have about 1200 SF. We bought our boiler , tubing, manifolds for about $3500.00 Yes the boiler was a huge chunk. Our Boiler is a Crown, not a Weil Mcann but a good one none the less. We also have an indirect tank for hot water. We put copper fin in an upstairs bedroom. All our main floor is hardwood, the tubing is stapled to the subfloor with plates and insulation. Saying that putting Pex in concrete is wrong is uninformed! There is a website that I frequent. www.heatinghelp.com Go there with your questions. Most of the people there are professionals in the warm water / steam heat business. They have a search for local pros that will help you out. I have read some good stuff here, but for you you need professionals. There is alot of misinformation out there.

    Good Luck

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    In the Trades Bob NH's Avatar
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    A proper radiant heating system in a concrete floor is expensive because it must have a lot of insulation below the concrete. Otherwise you are going to waste a lot of gas to heat the earth. Even with the best insulation you will lose some heat to the ground under the concrete.

    You or Keyspan can make a calculation to determine what is the best solution for the boiler. Let's say you are taking out a loan to build the addition. Let's say your payments on the loan are $150 per $1000 of loan. Keyspan can tell you how much you will save with the more efficient boiler. If your total loan payment + fuel cost with the more efficient boiler is the same or less than the total loan payment plus fuel cost for the less efficient boiler then you should get the more efficient boiler.

    Keystone should give you the same credit for the more efficient boiler that they give you for the less efficient boiler.

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    Computer Programmer Bill Arden's Avatar
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    Quote Originally Posted by Gnfanatic View Post
    1-) should i get their boiler or pay a little more and get a much more efficient one like a weil-mclain ultra series?
    Nope, get something cheep and spend more on things you can't replace latter.
    The savings between a 80% and a 90% is very small compared to a heat pump.

    Quote Originally Posted by Gnfanatic View Post
    2-)Do I need a tank?
    Yes. any system you make will need either a expansion or a small storage tank.

    Quote Originally Posted by Gnfanatic View Post
    3-) I have seen people use 1/2 inch pex, 5/8 or 3/4 for their floors. How do you know what size to use???
    This is a tricky question.
    The bigger the better, but there is a issue of cost.
    Important note I dont know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

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    DIY Member Gnfanatic's Avatar
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    Hey guys!
    Bob, my house is not on a slab! I have a full basement. I have 3/4 inch thick plank floor that the mud will go on.

    Bill, my friend gets 40% at a large plumbing chain here. so the cost between 1/2 and 3/4 and cant be that big of a difference. i didnt know they larger the better.

    Ed, good job! thats awesome. I am mech inclined, I can solder well and do electrical. I feel I can do this jsut need to be directed in the right direction. I neevr heard of Crown? I always hear Weil Mclain thats why i brought them up

    thanks guys!! getting some ideas here!

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    DIY Member edlentz's Avatar
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    I was fortunate that the distributor I bought from a. was a boiler installer (state licensed) b.sat down with me and drew out the whole system (took 2.5 hours!) before I gave him a dollar. Good luck getting that lucky! Tell you what I had a small bathroom that had Red Oak flooring 45 yrs old. I took it up and laid down tile over the pex stapled to the underlayment. I tell you what it warmed up right nice. It sure felt good in the winter!

    There is a series of pictures:
    Before:http://forums.invision.net/Attachmen...hment_ID=34216

    After:http://forums.invision.net/Attachmen...hment_ID=34220

    For more go to healtinghelp.com Questions and look for the Coupla Jobs thread.


    The previous post is correct that you need to insulate under a slab, but from what I have read the cost is well worth it. These guys do municipal garages with pex in the concrete. They know what they are doing.

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    DIY Member Gnfanatic's Avatar
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    so even though the floor is above a basement I still need to insulate it?? Good job BTW, big room you got there!! what size pex did you go with?

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    DIY Member edlentz's Avatar
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    OOPS that's not my room! That is one from the heatinghelp forum. My room was SMALL. There are alot of ways to install the radiant. I think you can layout the pex probably 1/2" on top, alot of installs use gypcrete (very lightweight) over the pex and then put down tile. I am not sure that you would need to insulate below.

  11. #11
    In the Trades Bob NH's Avatar
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    You don't need to insulate much or at all below if you want to heat what is below. If you don't want a lot of heat below you should add some fiberglass insulation below the tubes.

    For the radiant systems smaller pipe is probably less expensive for material for the same performance. It costs less and you need less concrete to cover it.

    The PEX tubing is a heat exchanger. Heat exchanger effectiveness is based on area. The surface area in a foot of PEX is proportional to the diameter but the material is proportional to the square of the diameter. Also, with larger diameter you need a lot more flow to get the velocity necessary for good heat transfer.

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    DIY Member Gnfanatic's Avatar
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    Thanks bob,. so I sure dont want to waste heat heating up the floor beams in the basement. So I will insulate the ceiling in the basement.I will look into whats good out there. I am looking into the ultra series which is about $3000 and the in-direct tank which is another $1000.I have another $2000 to spend on materials, so you guys are sayign thats not enough? Dont forget I already I have the cast iron baseboards.

    thansk again!!

  13. #13
    Retired Defense Industry Engineer jadnashua's Avatar
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    Before you do anything, you need to figure out the heat load of the building. Then, you can apportion it to each room by square footage, number of windows and exposure. Then, you can figure out how much pipe you need in each area. Depending on the design temps, running the pipe in tighter loops allows more heat to be transferred. There is a maximum supply temp that can be used to make sure the floor isn't overheated. The heat transfer decreases as the difference between the room and the supply. The ideal temp will depend on the insulation factors between the heat and the surface. Laying out the piping is also important - it is often a good idea to lay it out so the side just off the boiler is going around the perimeter, where it is coldest.

    You may make it on that budget, but it is likely to be very tight, and you'll need to do all of the work yourself. Keep in mind you will likely need to include permit fees.

    This is a complex project to both do well and end up with a comfortable and efficient end result. Do your homework.

    You could easily spend that much on the floor coverings themselves, so I'm assuming you have budgeted monies for that above and beyond.

    Before you tile, make sure your floor is sufficient to hold it up without deflecting too much and compromising the tile and grout. Check out www.johnbridge.com for help in tiling and use their 'Deflecto' deflection calculator to verify your construction. You wouldn't want to get all of the mudbed and tile down, then find it all cracks. It is highly recommended that you install a decoupling membrane between any radiant floor and tile. One brand is Ditra from www.schluter.com. The tile will also need expansion joints. The temperature swings with radiant heat can really stress rigid materials like tile.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Member Gnfanatic's Avatar
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    wow, some very interesting stuff and I appreciate it. I am a member of Johnbridge.com Very cool people there. I ordered Kerdi for my bathroom that I am building right now. I have money on the side for the mud and tiling, I am lucky that my fathers friend owns a a huge tile shop, he gives me everything at cost. Its funny you mentioned the deflection detection calculator. Of all the houses I have witnessed being cemented and tiled I never saw any of these "pro's" ever use these calculations. I was always told 3/4 thick mud min! I have 3/4 tonge and groove boards with 2x6 16 inchs on center. I am going to check out the calculator and do some math. I will also draw out the rooms, measure them and the windows. Guys, its VERY hard to find a REAL pro out there. How many of these so called plumbers would go measure rooms, windows and such? I rather do my homework, take my time and do it myself. I heard so many horror stories, they make the system ineffecient, poor design, poor electrical work, who got robbed etc etc! Thanks for the info , I appreciate it. Is there some sort of calculation to meaure heat load of my house????

  15. #15
    Retired Defense Industry Engineer jadnashua's Avatar
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    Just google "heat load calculator". No comment on which one(s) are any good. Many can be obtained as a free trial, so you could try several and compare the results. Some suppliers will take your house plan and calculate it for you and lay out the most efficient tubing install.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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