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Radiant with W/H

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  • #16
    Re: Radiant with W/H

    Originally posted by JCsPlumbing View Post
    RuudaGuy?
    He nodded off

    That turkey tryptophan is a powerful drug

    Comment


    • #17
      Re: Radiant with W/H

      Now as I understand it, radiant only heats objects...not air.

      Does that mean I can be in a room with a good radiant system operating correctly and be comfortable with a zero degree air temperature in the room?

      J.C.

      Comment


      • #18
        Re: Radiant with W/H

        You're an object, right?

        So you'll be warm

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        • #19
          Re: Radiant with W/H

          Fun to think about.

          J.C.

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          • #20
            Re: Radiant with W/H

            Sorry guys. My 3 year old daughter was begging me to play a game of Monopoly Junior.

            Not sure what to tell you about the interior walls thing, JC. I dont have to worry about that when just doing garages. Actually, maybe you could have all the loops exit each room through the doorways.

            One thing to consider is how the concrete guys are going to pour the slab. Are they doing it all at once, or splitting it up? If they split it up, they will put headers in to screed off of. Your tubing will have to go under those headers. Im assuming since its only 1200sf they will do it all at once.

            Ive never done a system that uses the same heater for domestic hot too. PC's idea is excellent!

            On my buddies 30x54 shop, they poured that floor in 2 sections. They poured 30x30 and 30x24. Instead of running my tubing under the header, I chose to zone the system and brought 1 5 loop manifold up in the 30x30 part, and had a 3 loop manifold for the 30x24 which I placed right by the heater. I ran 1-1/4" copper exposed on the wall hanging from Unistrut and B-line clamps over to the 5 loop.

            What type of construction is down there? Are the slabs done with a trench footing, or is there a foundation wall?

            Andy

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            • #21
              Re: Radiant with W/H

              I have installed about a half dozen such systems using both electric and gas fired hot water heaters. They never, ever work out right. Either the water heater self destructs and or the operation cost is sky high. Electric is by far the worst of all. Every single one of the systems I installed the tank has been torn out and replaced with either a Baxi or a Viessmann boiler, gas fired. Anyway, if you continue, make sure to install a tempering valve because you can not adjust an electric tank low enough for a cement slab, typically around 95 degrees is hot enough. High water temperatures will cause the cement to crack and powder in a short period of time.

              No, the air temperature can not be 0 and you will still feel warm. Radiant does allow you to slightly lower the room temperature but not that much.
              sigpic

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              • #22
                Re: Radiant with W/H

                Originally posted by Ruudacguy View Post
                Sorry guys. My 3 year old daughter was begging me to play a game of Monopoly Junior.

                Not sure what to tell you about the interior walls thing, JC. I dont have to worry about that when just doing garages. Actually, maybe you could have all the loops exit each room through the doorways.

                One thing to consider is how the concrete guys are going to pour the slab. Are they doing it all at once, or splitting it up? If they split it up, they will put headers in to screed off of. Your tubing will have to go under those headers. Im assuming since its only 1200sf they will do it all at once.

                Ive never done a system that uses the same heater for domestic hot too. PC's idea is excellent!

                On my buddies 30x54 shop, they poured that floor in 2 sections. They poured 30x30 and 30x24. Instead of running my tubing under the header, I chose to zone the system and brought 1 5 loop manifold up in the 30x30 part, and had a 3 loop manifold for the 30x24 which I placed right by the heater. I ran 1-1/4" copper exposed on the wall hanging from Unistrut and B-line clamps over to the 5 loop.

                What type of construction is down there? Are the slabs done with a trench footing, or is there a foundation wall?

                Andy
                This is the way I've seen it done also as PC says. All types of foundations. Crawlspaces with brick/block. Slab. Monolithic slab. Guess it just depends what your doing and the loads.

                J.C.

                Comment


                • #23
                  Re: Radiant with W/H

                  Originally posted by NHMaster3015 View Post
                  I have installed about a half dozen such systems using both electric and gas fired hot water heaters. They never, ever work out right. Either the water heater self destructs and or the operation cost is sky high. Electric is by far the worst of all. Every single one of the systems I installed the tank has been torn out and replaced with either a Baxi or a Viessmann boiler, gas fired. Anyway, if you continue, make sure to install a tempering valve because you can not adjust an electric tank low enough for a cement slab, typically around 95 degrees is hot enough. High water temperatures will cause the cement to crack and powder in a short period of time.

                  No, the air temperature can not be 0 and you will still feel warm. Radiant does allow you to slightly lower the room temperature but not that much.
                  I dare not question someone with more experience. But I will say that I've seen residential water heaters with circulating pumps on them and no Aquastat last 8 years or more.

                  Just replaced an Apollo forced air system heater that was over 10 years old. Don't know if the circulation cycle is the same though.

                  J.C.

                  Comment


                  • #24
                    Re: Radiant with W/H

                    In the 2nd response to your post, Plumberscrack posted a link to a Combi water heater by Bradford White which has a seperate coil that you can circulate radiant water through to use the tank water to heat it up.

                    I have seen this system - in fact I replaced one under warranty last year. Like NHmaster said, they never work out right.

                    Basically we got a job for a contractor doing the heating (hydronics-radiant floors, & gas fireplaces) of a fairly decent high end home in West Vancouver. One of the supervisors on a site built his Sisters House about 3-4 years ago. The company that won the PLumbing bid on our site (because after seeing their quality of work I can understand why we didn't underbid them for the Plumbing on this job) apparently did the job on his sisters house when he built his sisters house, but when the tank went after 3 years, suddenly they didn't "have time" to deal with it and were "too busy." So naturally we got called in to look at it. The other plumbers (hacks) already looked at it and confirmed the coil was gone and but again, were "too busy." So I got the job of ripping it out and replacing it under warranty (which was a bit of a ***** too). AFter viewing the system I can confirm the reason the tank failed was because it was cranked to as high as it can go - about 180, with a tempering valve to bump it down to 120-140. This was in the plumbers who installed's view, the only way this system would work as I talked to them about it and questioned why they didn't replace it (you should have seen how poor their workmanship was - they are also the first PLumbers I've ever see pull out a chain saw on a high end home, ever - I understand on condo's but a high end house?).

                    Anyways when I replaced it and set up the warranty tank and made a somewhat decent job of a neat install compared to what was there, I turned the new tank down after the homeowner let me know her concerns about the tank lasting. I told her dropping it down lower was the only way it would last, but then whenever they wanted to turn on their radiant floors on the floor the tank was on (about 6 loops on the bottom floor but they didn't ever hardly use the bottom floor - more for guests - the main and top floor were heated by a furnace) they would have problems with recovering hot water for domestic as the tank couldn't keep up to heating both for domestic water needs and heat-xchanging to the radiant coil.

                    Anyways, suffice to say a royal PITA.

                    Perhaps a Polaris might be the way to go although they're not known for having the best shelf life either.

                    But I think you're better off getting a small electric boiler and just having a seperate gas or electric hot water tank. An electric boiler, provided the power is there on their panel, could be a very good way to go because most electric boilers are quite inexpensive, they can actually modulate relatively well (by phasing/turning on elements in stages until the water temp being pumped is satisfied), require no vent or intake running ,and aren't that sophicated in all honesty. You could also get away with just one pump for a simple system with zone valves (a 1200 sq. foot house is 4-6 loops max, so probably 1 zone I'd imagine), and some electric boilers like the thermolec's come with outdoor resets which can further save on operating costs. Most Electric Boilers, say the Argo's for instance, should also have pump controls built in as well.

                    Comment


                    • #25
                      Re: Radiant with W/H

                      Thanks Scott K. You are one of the radiant gurus here. I have to say no to all recommended setups for rate of return vs. investment. Just better off doing a good engineered forced air system.

                      Wouldn't you say the reason that the house where you replaced the BW unit was having problems because the BW was just plain undersized to begin with? That's the reason they had it cranked so high to try and overcompensate.

                      Any heater or boiler can only produce X amount of BTU's with or without tank and those BTU's will only heat Y amount of space a certain temp.-degree rise with heat loss on a given days temperature.

                      So wouldn't the BW unit PC and you speak of perform fine within smaller sq.ft & thermal mass?

                      Thanks.

                      J.C.

                      Comment


                      • #26
                        Re: Radiant with W/H

                        I had a service call today on a radiant with W/H system. Kinda funny. The customer calls me and says he had one of my hackjob competitors out to his shop last Friday. When he called them he specified they send someone with radiant experience. When the tech arrived he admitted his experience was limited, but assured the customer he could fix the problem.

                        The AO Smith heater kept losing the pilot. The tech replaces the unitrol and the pilot assembly. When he was draining the heater the customer told the tech he should probably close some of the ball valves to prevent losing the water in the loops. Apparently when he said that the tech about jumped out of his shoes to shut off all the valves as fast as he could.

                        The customer left him alone the rest of the time. The tech came upstairs and said its fixed, collected a check and left. The customer walked downstairs and saw his 0-60 psi gauge pegged and almost back to the zero again.

                        This is where it gets funny.

                        The customer jumps in his vehicle and goes searching for the guys service van. During their conversation the tech mentioned he lived just down the road. He finds the guys house, knocks on the door and tells him theres something wrong. The tech said he needed to call the office so they could dispatch him again. The customer called the company 2 times today and never got a return phone call.

                        Enter me.

                        After 5 minutes of looking at the system and hearing this story I determine the system is air-locked. So I bleed each loop and get tons of air. I recommend replacing the 150psi T&P with a 15. Half hour later I'm on my way still laughing my *** off.

                        Andy

                        Comment


                        • #27
                          Re: Radiant with W/H

                          Originally posted by JCsPlumbing View Post
                          Thanks Scott K. You are one of the radiant gurus here. I have to say no to all recommended setups for rate of return vs. investment. Just better off doing a good engineered forced air system.

                          Wouldn't you say the reason that the house where you replaced the BW unit was having problems because the BW was just plain undersized to begin with? That's the reason they had it cranked so high to try and overcompensate.

                          Any heater or boiler can only produce X amount of BTU's with or without tank and those BTU's will only heat Y amount of space a certain temp.-degree rise with heat loss on a given days temperature.

                          So wouldn't the BW unit PC and you speak of perform fine within smaller sq.ft & thermal mass?

                          Thanks.

                          J.C.

                          JC - The problem with the house wasn't the tank or that it couldn't keep up. Sure - if you want to keep the tank at 160-180 and replace your tank every 3 years it'll work fine. But if you want to bump your tank down to 120-140, and you start taking a shower and then there's this big thermal mass of radiant water going through the heat exchanger at the same time, you'll quickly notice your hot shower turning warm and then lukewarm which is what happened when I had it set lower. You must also keep in mind it's still a natural draft appliance - not the most efficient to begin with, and if you want to have the tank last and still have the radiant going through it, you'd need some pretty sophisticated controls. The control system they had was very basic. It heats the basement, overshoots the basement temp because there wasn't anything there to control or modulate the water temp as it was just based on what ever came out of the heat excahgner going to the floors which lets the radiant water cool for a while, then when a call for heat comes, there is this large mass of water in the floors which must be heated up again and this is why when the tank was set lower and the radiant was going, you would get only warm water out of the tank for domestic. Also, what happens if you install this system and the tank goes? There goes their heat and hot water at the same time. You also have the issue of when the coil in the tank goes, which is what could happen (what happened when I replaced the one I mentioned), you get yucky heating water mixed in with your domestic water.



                          A 1200 square foot house, even with very cold outside design temps. doesn't take THAT much in the way of BTU's to heat it. You're probably looking at around 15,000-30,000 BTU's maximum heat loss, 30,000 being for this size of house with very cold winters and average insulation and 15,000-20,000 being more realistic. That is in the range of the smallest electric boilers offered by most manufacturers. For example I believe Argo offers an electric Boiler that is in the 6-8 KW range - 25 amps @ 230 V-ish with a 40 Amp breaker which is what I believe they recommend, and about 20,000 BTU's or so if I'm not mistaken with staged elements which acts like defacto modulation, sort of. Something like that or the next one up they offer would be perfect for your application and much better than a gas furnace for heating the house, and much better than a combicor type of system. It might even work out close cost wise. And this isn't even factoring in the quality of heat that radiant offers compared to forced air.

                          To keep the costs down I suggest you build your own manifold for the radiant instead of buying one. Buy some 1" x 1/2" Copper manifold stock, some 1" ball valves to put on the supply and return, some 1" x 1/2" reducers and 1/2" hose bibs to put on the other side of the manifold to help bleed it (on both the supply & return), and some of those 1/2" Dahl inline balancing valves that have the allen key adjustment on the return of each individual loop so you can help balance the loops as they will not all have the same footage. Install your radiant loops, build your manifold. Buy the proper (small) Pump and some fittings to install your electric Boiler, install it, have an electrician wire it, and you're off to the races.
                          If I bought my mom's rancher in the future, this is exactly what I would do to heat it as there aren't a lot of small modulating gas boilers out there but this is where the electrics pick up the slack - for the smaller applications.
                          Last edited by Scott K; 12-01-2008, 11:47 PM.

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                          • #28
                            Re: Radiant with W/H

                            Thanks PC & Scott K. Really good information. Getting much closer to understanding the logistics of radiant.

                            Off to think of more questions....

                            J.C.

                            Comment


                            • #29
                              Re: Radiant with W/H

                              Next question....ALREADY!

                              What are the benefits, drawbacks, and/or differences between open loop radiant & closed loop radiant???

                              J.C.

                              Comment


                              • #30
                                Re: Radiant with W/H

                                Can you elaborate between a closed loop and open loop? Never heard the termninology - are you talking about one that maybe uses domestic/potable as the heating medium, and one that uses dedicated water that is in the system for a long time?

                                If that is what you are describing, the benefits are obvious. Think cast iron/steel components - you want to use potable/new water all the time as your heating medium, you will have to go to all bronze/brass/non-ferrous or corrossion proof/resistant metals. In a closed system you can save $$$ because you can use cast iron pumps, steel buffer tanks, steel pipe, etc.

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