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Laurelie
Laurelie Member Posts: 16
edited March 2016 in Radiant Heating
About ten years ago, I bought a property with a DIY radiant heat system on an old Victorian in San Francisco. It was ordered it online from a company with the word radiant in front of the word company. ;-) You know the story goes downhill from there.

Boy is that company misleading. The point is, I am stuck with a Victorian with lots of their stuff that I cannot remove. For example, 1500 square feet of 7/8" PEX in the joists, and 800 square feet of 7/8" PEX in the concrete basement slab. ALL OF IT NON-BARRIER. And 7/8' in the joists isn't all that fun either.

Now, they say, as long as the temps don't go above 140 degrees, you are alright with non-barrier. But we know that's not really the whole truth. My temps, I must say, never go above 120. Y'all think I would be ok with a stainless fire tube boiler? The system works ok as is, but the utility bills are a fortune. And it's not all that cold where I live. It's just foggy, and the house would be 53-56 if I didn't run the radiant. I run it almost all year to keep the house 68 degrees. My bills are a fortune. I think it's the Takagi being wildly inefficient, which is why I want a real boiler.

I could tell the whole long story, but I will cut to the chase: I am trying to Number One, cut my gas and electric bills and Number Two, switch over from the tankless open system, to a closed system with a good boiler.

My problem is two part.

First, there is no way I can replace that non-barrier tubing. I'm stuck. So don't go there. My question is, can't I work around that? Any comments about what I can do to live with this for another 20 years? I know I should avoid cast iron pumps and boilers, but would I be ok with a stainless or brass pump set and an aluminum/copper boiler instead of the preferred stainless steel firetube style?

Second, if I have to live with a heat exchanger to avoid the ferrous portion of this bad situation, how much efficiency exactly do I lose by using a plate heat exchanger? My whole goal here is to lower my heating bills. If I told you what I pay in Sunny San Francisco to run this system off that blasted Takagi, you'd have me committed.


I want to have a boiler and an indirect hot water heater, ideally. I just want this to be more efficient.


Any ideas? I am eager to hear! Thank you all!

Comments

  • Snowmelt
    Snowmelt Member Posts: 1,334
    I'm not a fan of that set up you have, but I'm concerned about the spacing your using, the pump your using. It may not be the takagi that's ging you problem it maybe the pump your using? Off the top of my head.
    So I have a few questions:
    What size pump?
    What's your square footage of house compared to how many btu will heat your home?
    How many loops do you have on your radiant and howling are each runs?
    Do you have an air seperater on your system?
    Are you set up primery/secounday.

    I'm the takagi go to guy in nj. I have one in my basement doing a snow melt system. Also doing a 30 x 30 great room with radiant floor all been working well past 4 years.

    Also do you have any pictures.
  • Ironman
    Ironman Member Posts: 6,890
    You're gonna need the put a heat exchanger in to isolate any new boiler from the non barrier tubing. Even the stainless steel ones won't be warranted if connected to non barrier pex.

    Just make sure the heat exchanger is properly sized so you can keep your boiler water temps as low as possible for better efficiency with a mod/con.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    RobG
  • Laurelie
    Laurelie Member Posts: 16
    edited January 2015
    So are you saying that with non-barrier tubing running at 120-125 degrees, no boiler at all, nada, nothing can handle it? I thought that an aluminum/copper boiler like the Buderus or Challenger would work, because aluminum and copper aren't effected by ferrous material.

    Any by the way, I have a nice metal mesh strainer on the system that removes the major rusty and serious gunk. The water has run relatively clean for going on eleven years. I do have to clean out the teeny takagi filter once a month, tho.

    To answer the other issues, I changed the pumps out to cast iron Grundfos Alphas two years ago (before I knew not to use cast iron) and that actually lowered the electrical use by about 70%. Impressive.

    I also, two years ago, I put in a pressure reducer to lower the pressure of the open system because I was springing leaks in their fabulous tubing! Leaks in the Pex, which the company called radiant couldn't explain. That burned me up. The Pex couldn't handle 60 psi. But at 15-20psi, there have been no leaks. At that time, I started using a second takagi unit for hot domestic water

    I have four loops upstairs in the joists (1400 square feet) and two loops in the basement slab (800 square feet).

    My delta t is always right on the money--20 degrees cooler coming back.

    Hope this helps.

    I just think that paying $300-500 per month in gas to run that Takagi is outrageous, and I would hope that a nice boiler would lower that.

    It does heat the house well, tho. But we are talking San Francisco, where during the cold snap two weeks ago, the temps got all the way down to 44 degrees! BRRRR.


    KIDDING.

    And that's the point. If I were back East, I would have frozen to death. $500 to get a house from 53 degrees to 68 degrees is sad.

    BTW, when I fire up the Takagi to 135 degrees, I can get the house up to 75 degrees.

    It really is a much longer story than this... A neighbor who went from the Takagi open system to the Triangle Tube Challenger said his bills dropped like a rock, from $400 per month gas, to about $120-150.
  • Ironman
    Ironman Member Posts: 6,890
    Oxygenated water produces a lot more issues than just causing ferrous materials to rust. A properly sized HX and a stainless circ on the open side are not that big of a deal. You've already been burnt by the corner-cutting approach, why continue that approach if you're wanting to make the system right?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    RobG
  • Zman
    Zman Member Posts: 7,355
    I would certainly not install an aluminum boiler with your setup.
    Triangle tube prestige fire tubes do very well in O2 environments. I spoke with the regional trainer a few years ago. At that time triangle tube had no reservations about it. He did note that the TT Smart indirect tank was not appropriate as it has ferrous components.
    Be sure to pick all the little parts carefully. The expansion tank air eliminator and circulators should absolutely be non ferrous.
    I rarely disagree with Bob but I do on this one.
    Make sure you clean the system thoroughly and go for it..
    Carl

    PS
    I am surprised that the Takagy is that inefficient. Had you not noted the neighbors savings claim (be careful with those). I would have suspected poor insulation especially at the joist rim and the crazy suspended pex as the main cuprits.


    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Snowmelt
    Snowmelt Member Posts: 1,334
    Yea I'm surprised also, I think you have an insulation isue more then the takagi issue, as far as the Pex is concerned, you have to see what brand of pex you have in your floor. Radiantfloor company doesn't make there own pex.
    At 120 degrees the pex should be able to handle any kind of pressure your house has.
    Even the copper heat exchanger & air doesn't mix. I personally install a air seperater before the takagi, so no micro air bubbles get hung up in the heat exchanger. You do need someone to come by and do a heat lost calculation. If you go to taco-hvaç they have a nice website that you can learn how to do a heat lose calc for the house. I'm thinking eirher your near boiler piping or your pump.

    If you go with another machine utica has a machine with the same kind of copper heatexchanger, can use the same venting ( cat III ) also had a heat exchanger to seperate the domestic water.
    As far as the micro bubbles are concerned I would use a air seperater right before the machine.
  • Rich_49
    Rich_49 Member Posts: 2,693
    Laurelie , What is your domestic hot water usage like in GPD ? Are there kids , how old , active , couch potato ? What type of shower heads and how many baths ? I think I have an idea that I would like everyone to hear and opin on .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • Laurelie
    Laurelie Member Posts: 16
    So bottom line, may I ask everybody, are you all saying that a Takagi doesn't use all that much more gas than a boiler?
    Rich said:

    Laurelie , What is your domestic hot water usage like in GPD ? Are there kids , how old , active , couch potato ? What type of shower heads and how many baths ? I think I have an idea that I would like everyone to hear and opin on .


    As I said, the system was "open" and it's now closed. (I use another takagi unit for the domestic hot water). Our use is on the heavy side. We have tow adults and five kids. The kids shower, but both adults are bathers. We take a nice hot clawfoot tub every night.

  • Snowmelt
    Snowmelt Member Posts: 1,334
    That's what we're saying, there's something else going on that your using that much gas. I seen some crazy things. Turn all your gas appliance off see if the gas meter is still turning.

    What rich ment is how many gpm of hot water do you use. If you have a remote on your unit you can the remote set on gpm to tell how much is comming out of the unit.

    We still need to see pictures of the set up.
  • RobG
    RobG Member Posts: 1,850
    I agree with Bob, go to a mod/con boiler and either use all non-ferrous components or a heat exchanger. Make it a closed system and use an oxygen scavenger chemical treatment annually. You can clean the Takagi and save it for when the other one dies.
  • SWEI
    SWEI Member Posts: 7,356
    When the Alpha eventually gives out, make sure you replace it with a stainless volute model.
    Warmfoot2