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Homeowner Forum / Construction / December 2008Radiant Floor Heating Question (boiler vs water heater)
In a hydronic floor heat system, what is the best way to heat the water in the pex tubing? The initial study of the building design recommends a 16800 BTU 85% efficient boiler ($2000 US). I am hearing about possibly a more efficient way using two 90% efficient 60 gal water heaters. Can anyone make some suggestions to me? I live in Northern Colorado. Project description: 42 x 80 Pole style building, single level (metal siding + metal roof), 12 ft side walls FLOOR: 1 1/2" "Blue board" foam insulation on top of pea gravel - 5" concrete slab w/ pex tubing on 12" centers - 3 zones (3750' of 1/2" tubing in approx 250' runs INSULATION: Walls- R-26 -- Ceiling- R-38 Thanks! > In a hydronic floor heat system, what is the best way to heat the water > in the pex tubing? [quoted text clipped - 17 lines] > > Thanks! It is possible to make hot water heaters work with radiant flooring but in most cases the duty cycle is far greater than the hot water heater was ever intended for. You can figure what that does to the life expectancy. > FLOOR: 1 1/2" "Blue board" foam insulation on top of pea gravel - 5" > concrete slab w/ pex tubing on 12" centers - 3 zones (3750' of 1/2" tubing > in approx 250' runs Interesting floor construction. In the UK for a non structural floor we would typically build he following top down... 2.5" concrete with heating pipe in 3" foam insulation Damp proof membrane (plastic sheet) Sand "blind" (to stop plastic sheet being punctured) 6" Compacted stone chips (called hardcore in the UK) >> FLOOR: 1 1/2" "Blue board" foam insulation on top of pea gravel - 5" >> concrete slab w/ pex tubing on 12" centers - 3 zones (3750' of 1/2" [quoted text clipped - 10 lines] > Sand "blind" (to stop plastic sheet being punctured) > 6" Compacted stone chips (called hardcore in the UK) In the us, slab floor construction is typically under the entire house so it is structural. >>> FLOOR: 1 1/2" "Blue board" foam insulation on top of pea gravel - 5" >>> concrete slab w/ pex tubing on 12" centers - 3 zones (3750' of 1/2" [quoted text clipped - 13 lines] > In the us, slab floor construction is typically under the entire house so > it is structural. 5" doesn't sound very thick for a house. Is that timber frame?. Over here a garage or shed base is typically 4". > In a hydronic floor heat system, what is the best way to heat the water > in the pex tubing? [quoted text clipped - 17 lines] > > Thanks! Is this a troll, 16800 Btu has to be a typo, you do mean 168000 I hope I hope. You want efficency and you discuss 85% efficent boilers when up to 98% are made !! What boiler are you looking at. Tell us all who makes a 90% efficent tank water heater... Answer nobody makes a 90% efficent fossil fuel water tank. Learn about EF- Energy Factor ratings, and show us the tank. And a tank isnt designed for long life but it truely aint efficent. 1.5" Blueboard is R 7.5,, 1.5" foil faced Polyisocyanurate is R 10.5 with an added radiant barrier, which is still not optimal R value for concrete radiant heat. Walls R 26, Ceiling R38, it sounds off. What is construction and type of insulation You have lots a learnin to do wilma fingerdo, cause someones lyin to you. >> In a hydronic floor heat system, what is the best way to heat the water >> in the pex tubing? [quoted text clipped - 26 lines] > Energy Factor ratings, and show us the tank. And a tank isnt designed > for long life but it truely aint efficent. You seem pretty sure of yourself ... for being wrong. http://www.americanwaterheater.com/products/pdf/lpg100.pdf > 1.5" Blueboard is R 7.5,, 1.5" foil faced Polyisocyanurate is R > 10.5 with an added radiant barrier, which is still not optimal R value [quoted text clipped - 3 lines] > type of insulation You have lots a learnin to do wilma fingerdo, cause > someones lyin to you. More than one person is lying to Wilma. > >> In a hydronic floor heat system, what is the best way to heat the water > >> in the pex tubing? [quoted text clipped - 40 lines] > > - Show quoted text - I see your as dumb as her if you dont know facts. Gees, what ignorant folks believe. >>>> In a hydronic floor heat system, what is the best way to heat the water >>>> in the pex tubing? [quoted text clipped - 31 lines] > I see your as dumb as her if you dont know facts. Gees, what ignorant > folks believe. What part of the Polaris efficiency specification did you not understand? > >>>> In a hydronic floor heat system, what is the best way to heat the water > >>>> in the pex tubing? [quoted text clipped - 35 lines] > > - Show quoted text - Polaris, Ao Smith, condensing, are not 94-96% efficent. www.energystar.gov publishes efficency ratings for all tanks made. Efficency of a tank is rated as EF or Energy Factor, the number rating of 85 means 85 cents of every dollar you spend heats the water. I have a $2000.00 Ao Smith Cyclone condensing tank of thermal and burner efficency of 93% but its EF rating is about 83, and all boilers are at least 82% efficent today. 95 or so % of all Tank water heaters sold today in the US even the ones labeled High Efficency are in fact only 55-65 EF. The government still hasnt set a standard yet, its a scam to the uneducated. The lowest gas tankless is 83 EF and a condensing Takagi is 93EF. that is the highest efficency water heater I know of made today, so what you see is most always no better than 55-65 EF or 45-55 cents of every dollar you spend heating water goes up the chimney ! Boilers can be much more efficent, the AFUE ratings reflect use, like EF rating does on tanks. There are many 93-96% efficent Ng condensing boilers out, that are the best for Radiant tube sine Radiant uses realtivly low water temps and Condensing boilers drop dramaticly in efficency at over 140F, there is one I know of from canada that is AFUE 98% efficent, and the best tank is maybe 83 EF that I know of. EF is not a rating Tank manufacturers publish often, or like to talk about, because it highlights tank limitations in true efficency OP doesnt discuss Condensing units, but is in fact looking at 83% boilers, when 96 is easily avalaible, and most likely is looking at Two, 55-65 EF tank, now thats a waste of money. First 2 tanks would be less efficent than one and she doesnt need 2, but tank are not designed to last as home heaters. The last I read Energy Star is still working on a tank specification. Op is best with a 96-98% AFUE condensing boiler, not a 55-65 % efficent water tank made for showers. Find the EF rating on Polaris and post it, Ao Smiths site wont post all EF numbers on their super expensive Condensing units, but I own one. On Dec 2, 1:46 pm, Voyager <m.whit...@computer.org> wrote: > OP doesnt discuss Condensing units, I guess they aren't mandatory in the US? In the UK all new installations or replacement boilers (tank heaters) have to be condensing. Been like that since 2005. >>>>>> In a hydronic floor heat system, what is the best way to heat the water >>>>>> in the pex tubing? [quoted text clipped - 70 lines] > and post it, Ao Smiths site wont post all EF numbers on their super > expensive Condensing units, but I own one. Sure, you can define and redefine efficiency any way you want. You simply said "efficiency" in your post, you didn't say "energy factor." I could also redefine "efficiency" as total energy leaving the ground vs. what ends up as heat in my water tank including the energy required to extract and transport the fuel to my house and then claim that water heaters are only 30% efficient. If you want to play definition games. Overall system efficiency is not a simple equation and should include economic efficiency as well. Often the extra cost of the ultimate highest energy efficient boiler or furnace isn't justified economically. When I built my house I went with a 92% efficient (AFUE) furnace vs a 95% for two reasons: 1. The cost delta was substantial at that time and the payback period would have likely exceeded the life of the furnace. 2. The contractor told me that the newer furnace had been very troublesome compared to the 93% model which had been on the market several years longer. Apparently, the variable speed motor and variable flow gas valve hadn't yet been fully sorted out from a reliability perspective. Using a water heater sounds odd for a building of the size the OP is looking at, but if there are other needs for a large water heater anyway, then using a large water heater vs. a boiler and a water heater, might make sense economically. Then again, maybe a boiler with a heat exchanger to heat water for non-heating purposes might make more sense. > >>>>>> In a hydronic floor heat system, what is the best way to heat the water > >>>>>> in the pex tubing? [quoted text clipped - 102 lines] > > - Show quoted text - I did not say Energy Factor, wait one minute, I am the ONLY person to talk EF Sure my heat guy said condensing is an issue, his stupidity was the issue. Show me one study the states condensing wont pay off, I mean wake up, at a minimum you get 10% savings. How many folks here have tankless water heaters in the US, Naw you guys are all to smart for those. I have one in my house and in summer my gas bill went down from 45$ to 9 month, mine was a 450$ Bosch, I get a 4 yr payback and its maybe 6yrs old now The only way a 55-65% efficent tank makes sense is if you are dumb, and you cant drink or shower from water for heating so if OP has 2 tanks to heat the OP needs a 3rd unefficent junk to heat water. > >>>>>> In a hydronic floor heat system, what is the best way to heat the water > >>>>>> in the pex tubing? [quoted text clipped - 102 lines] > > - Show quoted text - You mean you went with an 82% unit, right. My installer tried to talk me out of condensing, in fact 90% still do. They key is to get what works. Condensing furnaces have been a non problem issue for at least 10-15 years, condensing boilers at least 6 years, condensing Oil boilers are new, but furnaces have been out a long time, its up to you to learn facts. Bottom line condensing have a minimum savings of 12%, no honest study that reflects true energy price increases and future trends will show non condensing best. > You mean you went with an 82% unit, right. My installer tried to talk > me out of condensing, in fact 90% still do. They key is to get what [quoted text clipped - 4 lines] > no honest study that reflects true energy price increases and future > trends will show non condensing best. No, I went with a Lennox Elite that is ~92% AFUE rather than the top of the line ~95% unit. Both are condensing designs. The difference is that mine has a single speed blower motor and, I believe, a two-stage gas valve. I haven't checked the specs lately, but at this time (8 years ago) the top of the line Lennox had a variable speed blower motor and a variable flow gas valve. Word was that both were causing problems at the time (again, 2000 era). > > You mean you went with an 82% unit, right. My installer tried to talk > > me out of condensing, in fact 90% still do. They key is to get what [quoted text clipped - 12 lines] > and a variable flow gas valve. Word was that both were causing problems > at the time (again, 2000 era). Yes the GE VSDC motor was an issue and still might be, even with a redesign by moving the electronic to keep them cooler, I have a Lennox like yours at a location its a good unit and efficent. If you get VSDC the 10 yr warranty is necessary. >>> You mean you went with an 82% unit, right. My installer tried to talk >>> me out of condensing, in fact 90% still do. They key is to get what [quoted text clipped - 16 lines] > like yours at a location its a good unit and efficent. If you get VSDC > the 10 yr warranty is necessary. I figured at a lost of only 2% AFUE, it was worth it to avoid the problems and stay with the slightly less efficient, yet apparently vastly more reliable model. > >>> You mean you went with an 82% unit, right. My installer tried to talk > >>> me out of condensing, in fact 90% still do. They key is to get what [quoted text clipped - 22 lines] > > - Show quoted text - I was looking at vsdc when I put mine in, luckily I didnt do it either, but you say yours is 2 stage gas, so your blower is 2 speed, and you must have the 2 stage stat, right, the blower must go go high on high fire or the furnace exchanger overheats and its life is being shortened alot. Listen for the blower kicking on high , Mine is set for maybe 2-3f for when high fire is called for, you should get a probe thermometer like a meat thermometer and insert it at the top of the furnace to check the temp output, there is a specified range and exceeding it really shortens the life of the aluminum heat exchanger, I found my tech never checked mine and I was over the limit so I lowered gas input. I think I have the same model as you and have a 2 stage thermostat. One thing that will fail is the heat exchanger its aluminum or steel, not Stainless steel and I have heard they are failing, keeping temp in the low recommended range will increase its life alot. >>> In a hydronic floor heat system, what is the best way to heat the water >>> in the pex tubing? [quoted text clipped - 39 lines] > > More than one person is lying to Wilma. Thanks for the reply, I mean 168000 btu. Its spray foam and cellulose insulation. "Pole Barn" type construction. >> Tell us all who makes a 90% efficent tank water heater... Answer >> nobody makes a 90% efficent fossil fuel water tank. Learn about EF- [quoted text clipped - 3 lines] > You seem pretty sure of yourself ... for being wrong. > http://www.americanwaterheater.com/products/pdf/lpg100.pdf How much does that puppy sell for?  SignatureArt > >> Tell us all who makes a 90% efficent tank water heater... Answer > >> nobody makes a 90% efficent fossil fuel water tank. Learn about EF- [quoted text clipped - 8 lines] > -- > Art I am wrong , wake up and show me an EF rating, the one they dont publish, the one that IS unit efficency. They dont show it because it is not good and will loose customers. >>>> Tell us all who makes a 90% efficent tank water heater... Answer >>>> nobody makes a 90% efficent fossil fuel water tank. Learn about EF- [quoted text clipped - 10 lines] > publish, the one that IS unit efficency. They dont show it because it > is not good and will loose customers. I'd have to have loose customers. :-) >>>> Tell us all who makes a 90% efficent tank water heater... Answer >>>> nobody makes a 90% efficent fossil fuel water tank. Learn about EF- [quoted text clipped - 10 lines] > publish, the one that IS unit efficency. They dont show it because it > is not good and will loose customers. Yes, it would be bad to have loose customers. The tight ones are much better, but they don't spend as much money. > >>>> Tell us all who makes a 90% efficent tank water heater... Answer > >>>> nobody makes a 90% efficent fossil fuel water tank. Learn about EF- [quoted text clipped - 15 lines] > > - Show quoted text - Maybe if they knew and had options you would get more customers, few are aware of the truth with water heaters >>>>>> Tell us all who makes a 90% efficent tank water heater... Answer >>>>>> nobody makes a 90% efficent fossil fuel water tank. Learn about EF- [quoted text clipped - 15 lines] > Maybe if they knew and had options you would get more customers, few > are aware of the truth with water heaters Well, I don't sell anything so it is of no concern. :-) >>> Tell us all who makes a 90% efficent tank water heater... Answer >>> nobody makes a 90% efficent fossil fuel water tank. Learn about EF- [quoted text clipped - 5 lines] >> > How much does that puppy sell for? Big $$$. I wouldn't buy one. > >> In a hydronic floor heat system, what is the best way to heat the water > >> in the pex tubing? [quoted text clipped - 40 lines] > > - Show quoted text - Ok whats the lie... And you are a Pro ! Lets see what you really know. On Dec 1, 2:02 pm, Wilma Fingerdo <papercliphun...@gmail.com> wrote: > Tell us all who makes a 90% efficent tank water heater... "In tank" electric heating elements are 100% efficient. Where else does the energy go if not into heat? Most are pretty quiet. Sorry if anything has been lost in translation (I'm English). > On Dec 1, 2:02 pm, Wilma Fingerdo <papercliphun...@gmail.com> wrote: > [quoted text clipped - 4 lines] > > Sorry if anything has been lost in translation (I'm English). He did qualify it as being "fossil fuel" powered and electricity may come from hydro or nuclear and thus not be fossil fuel. However, I provided a link to a fossil fuel unit that was still well above 90% efficient. > > On Dec 1, 2:02 pm, Wilma Fingerdo <papercliphun...@gmail.com> wrote: > [quoted text clipped - 9 lines] > provided a link to a fossil fuel unit that was still well above 90% > efficient. Learn about Certified, EF Tank ratings, from the Government at www.energystar.gov EF is how a tank is rated, AFUE is a boiler rating, SEER is AC. That "well above 90% efficent Polaris" I bet is near 83-85% EF as is my Condensing $2000.00 AoSmith. Look at AoSmith, Cyclone and Vertex line, the same top end stuff as Polaris. My last Ao lasted near 20 years in commercial heavy use, AoSmith is a top commercial manufacturer. To heat a house even more efficently, get a domestic water heater built to it, or use a Condensing 93 % 93EF ! Takagi Ng tankless. And then there are more options. On Dec 2, 2:40 pm, "Cwatters" <colin.wattersNOS...@TurnersOakNOSPAM.plus.com> wrote: > On Dec 1, 2:02 pm, Wilma Fingerdo <papercliphun...@gmail.com> wrote: > [quoted text clipped - 4 lines] > > Sorry if anything has been lost in translation (I'm English). Thats electric, and it really 99-100% efficent, OP is talking Gas. On Dec 2, 2:40 pm, "Cwatters" >> Sorry if anything has been lost in translation (I'm English). >> >Thats electric, and it really 99-100% efficent, OP is talking Gas. Ah thanks. We would call them Boilers or central heating boilers. Since April 2005 all gas boilers in the UK have been condensing types. Non condensing types can only be about 88% efficient but condensing types can be 90+% efficient.. Example: http://www.worcester-bosch.co.uk/installer/products/gas-fired-boilers-and-systems The oil boiler I have is 92-93% efficient... http://www.grantuk.com/product/28 but there are different ways to calculate efficiency. This explains how to get a headline rate of 102% ... http://www.blesi-evans.com/102%20percent%20efficiency.pdf How do running costs compare for electric, gas, oil in the USA? We have a comparison site here... http://www.nottenergy.com/energy-costs-comparison3 For what it's worth it assumes 90% efficiency for a gas boiler. On Dec 3, 10:41 am, "Cwatters" <colin.wattersNOS...@TurnersOakNOSPAM.plus.com> wrote: > On Dec 2, 2:40 pm, "Cwatters" > [quoted text clipped - 19 lines] > > For what it's worth it assumes 90% efficiency for a gas boiler. England an energy Exporter has had the foresight to mandate condensing heat units, here in the dumb ol USA 83% efficent is still pushed because installers like the "easy" instal and idiot homeowners are to dumb to do the math, its a joke, we import oil and we allow 83% efficent heat. Water heater tanks are just one reason we as a nation use a majority of the world energy by % of population. Its a fact, in new construction a hot tub is more common than a high efficency heat plant. > On Dec 3, 10:41 am, "Cwatters" > [quoted text clipped - 36 lines] > > - Show quoted text - That's pretty easy when your entire country is the size of some of our states. Besides we have a reputation as consumers of 25% of the worlds energy to hold up over here on our side of the pond. My hot tub is electric so that 100% efficiency but the insulation is probably only r6 or so I'd guess. >> On Dec 3, 10:41 am, "Cwatters" >> [quoted text clipped - 30 lines] > My hot tub is electric so that 100% efficiency but the insulation is > probably only r6 or so I'd guess. It is 100% efficient at the point of use, but when you factor in generation and transmission losses, electric power isn't always such a good deal. Even though, as an EE, I'm partial to electricity the is that it isn't always the best solution when total system efficiency is considered. > JamesGan...@gmail.com wrote: > >> On Dec 3, 10:41 am, "Cwatters" [quoted text clipped - 39 lines] > > - Show quoted text - For few electric is acceptable since in few places is electricity as cheap per BTU as Ng. How many homes in your area have Electric boilers and furnaces, in my area none, and they are made and cheaper to make. A hot tub in in the catagory of pissing money down the drain. > > JamesGan...@gmail.com wrote: > > >> On Dec 3, 10:41 am, "Cwatters" [quoted text clipped - 46 lines] > > - Show quoted text - I'm guessing you don't have a hot tub. Pretty nice at the end of a long day :-) > England an energy Exporter.. Sadly no longer. We became a net importer of oil in 2005... http://www.theoildrum.com/files/UK_oil_imp_exp.png It's not on that graph but we've also been importing natural gas. Whole of europe is now dependant on Russia for natural gas. Something like 25% of the natural gas burnt in Europe now comes from Russia. So much for energy security. On Dec 7, 8:34 am, "Cwatters" <colin.wattersNOS...@TurnersOakNOSPAM.plus.com> wrote: > > England an energy Exporter.. > [quoted text clipped - 4 lines] > natural gas burnt in Europe now comes from Russia. So much for energy > security. The real point is Englands climate is more mild than the US, there are areas here that people spend a major amount of their income heating in winter, but in the US heating companies sell and would rather instal 83% sytems, here is where they should be banned, many still buy them today in new construction, and use the saved money for a hot tub. We dont have an energy saving policy here. |
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