Browse Forums Heating, Cooling & Insulation 1 May 05, 2009 10:05 am Hi All, I'm a new member here. My name is Jag. I'm building my new home in Canberra and I'm confused on what type of heating I should go with. I have read past threads about hydronic heating here at homeone but none answers my specific questions. So I thought of creating a new topic. I hope many of you here would have heard about coldbusters (coldbusters.com.au) and their electric on slab (not in slab) heating. They say it is very efficient and cheap form of heating. I don't know if it would be good compared to hydronic heating. I'm planning to use gas hot water system for hydronic. I'm confused which one is better to run. If any of you have used hydronic can you please share your thoughts about running cost? Also can you please let me know how much area you are heating? etc.. Cheers, Jag Re: Hydronic heating Vs On slab heating - running cost 2May 05, 2009 12:22 pm My running costs will be virtually zero. But it will cost to get the system . I will be using solar hot water panels to feed a tank that will then connect to the in-slab hydronics. There will be no boost. If there asre several cloudy/raining winter days in a row, I know the house will get too cold, but then you just put on a jumper. I expect this will only happen a couple of days each year. I suspect gas-boiler hydronic systems would cost quite a bit to run, especially if you don't insulate the underside of the slab too well. And electric systems would cost even more. Yes, it will be interestign to hear from anyone who does have an in-slab system, what the running cost is. Demolition August 2009, Construction Started September 2009, Completed December 2010 Re: Hydronic heating Vs On slab heating - running cost 3May 05, 2009 3:09 pm Hi Casa2, I enquired about solar hydronic heating they said it would cost approximately $25K to get it installed. I won't get a government rebate (as it is new home). Even I'm expecting to hear from someone who uses electric on-slab or gas hydronic heating. Cheers, Jag Re: Hydronic heating Vs On slab heating - running cost 5May 05, 2009 9:36 pm Gas hydronic, last winter paid $415 for gas bill for 58 days, house of about 25 squares living. There are of course many variables in this, from ceiling height, set temperature, etc. If you want me to be more specific I can. Re: Hydronic heating Vs On slab heating - running cost 6May 06, 2009 1:35 pm Hi All, I work for a company who supply and supply & install electric and Hydronic floor heating systems. Not a day goes by where I am asked about running costs on both electric floor and Hydronic gas floor heating and how the different types compare. A note on estimate running costs quoted by most manufacturers: these are calculated mathematically on the assumption the build has good insulation and occupants exercise good heat loss management techniques. The estimate calculations quoted are often based on the heating system drawing full load for x hours, then duty cycling X% per hour thereafter. If your actual site conditions deviate from the assumptions made for calculation purposes, so too will your running costs. In most instances, response times for Hydronic gas and electric slab is 8 hours, whilst above slab floor heating is 1 hour. Also, it is assumed thermostatic duty cycles of 35-40% are achievable. If we take a look at 'worse case' running cost scenarios for a home requiring comfort heat during mornings and evenings, Amuheat' electric and Hydronic floor heating systems running costs would be as follows (by worse case I mean the floor heating system draws the max energy load during hours of operation, for reasons such as great heat losses through exposed windows or cold drafts, incorrectly set thermostats, etc): Hydronic in-Slab- a typical gas boiler with a min/max output of 17/30kW has a min/max consumption of 77/132MJ/h. A heat output of 17kW will be sufficient to heat living areas up to 150m2. Assuming you run your floor heating system for a full quarter, at full capacity between 4pm till 12am, then again 3am till 8am for 3 months, the max total MJ consumption is 90090MJ. Max usage rates for the 13 hour per day, 90 day period totals $1502. (Rates ref: http://www.agl.com.au/home/accountenqui ... ntial.aspx) Electric in-Slab - a similar space of 150m2 would require an in-slab floor heating system with a heat output of 24kW. Assuming you run your slab floor heating system for a full quarter, on off-peak and shoulder rates at full capacity between 10pm till 7am then 1pm till 5pm in ACT, the max total kW consumption is 28080kW. Max rates for this 13 hour per day, 90 day period totals $2724. (Rates ref: http://www.actewagl.com.au/prices/home/ACT/elec.aspx) Electric Above Slab - the same 150m2 space would require an above slab under tile or under carpet floor heating system with a heat output of 14kW. Assuming you run your heating connected to a time of use meter, on demand for a full quarter, at full capacity between 4pm till 12pm then 5am till 8 am in ACT, the max total kW consumption is 13860kW. Max rates for the 11 hour per day, 90 day period totals $1938. (Rates ref: http://www.actewagl.com.au/prices/home/ACT/elec.aspx) Based on the above 'worse case' scenarios, Hydronic gas is clearly the most efficient heating solution if you are planning on heating the entire space at all times . However, typical Hydronic slab and electric slab heating is slow to respond, often requiring up to 8 hours of energy input to have an effect in raising the rooms ambient temperature. These systems are turned on at the beginning of winter and left to run. Zoning for slab heating only helps achieve comfort levels in rooms with different orientations, heat losses etc. To run a floor heating system constantly to work around slow response times to have stored heat in case you need it, may be seen as a waste of energy use in rooms you are not using, considering one cannot be in all rooms of the home at all times. In addition to the benefits of zoning to achieve comfort levels in rooms with differing heat losses, zoning an above slab heating system does achieve savings on running costs, since rooms not in use can be turned down or off. You don't need to think ahead and ensure your heating is turned on a day before with above slab heating, when you turn it on the floor is warm within an hour and control can be done manually or via programmable thermostat. If we look back to 'worse case' running cost estimates, if at any one time just 22% of the above slab heating is turned off, 'worse case' above slab heating running costs are comparable to Hydronic gas floor heating. Often, more than 22% of a home’s floor heating can be turned down or off at any one time. In deciding which way to go, identifying your desired pattern of use upfront is possibly one of the most important factors when designing your floor heating system. If you intend to heat the entire home at all times and you have access to gas supply, a Hydronic gas slab option is clearly the way to go over an electric slab system or, if budget allows, a hydronic floor heating system with solar collectors with storgae and a gas boost. If you are more likely to only require heating in select zones at differing times of the day, on random days, and you are fixed in choosing Hydronic over electric, look into a gas multizoned Hydronic floor heating system with set-back. It offers quicker than normal response times and better control of running costs as compared to single zoned gas hydronic floor heating systems. If however your budget does not allow for this, an above slab electric system is the best choice. Of course, there is nothing stopping you designing a solution that incorporates both types - electric above slab for zones likely to require random use outside normal winter periods (say bathrooms, laundries, cooler basement rooms) and Hydronic slab for zones used throughout the winter months. Hope the above helps in making an informed decision. Alfred Re: Hydronic heating Vs On slab heating - running cost 7May 06, 2009 2:52 pm amuheat Hi All, Based on the above 'worse case' scenarios, Hydronic gas is clearly the most efficient heating solution if you are planning on heating the entire space at all times . However, typical Hydronic slab and electric slab heating is slow to respond, often requiring up to 8 hours of energy input to have an effect in raising the rooms ambient temperature. These systems are turned on at the beginning of winter and left to run. Zoning for slab heating only helps achieve comfort levels in rooms with different orientations, heat losses etc. Alfred Hi Alfred, thanks for the post ! Is the math the same for Hyrdronic in Slab versus Hydronic Panels ?? * Are we there yet ? Demolition has come and gone ! yippeeee..hang on that was months ago !! come on Mr Builder, dig a hole at least Finaly ! Hole Dug ! well done darren 20/06/2010. Slab is down ! Framing is complete 20/10/2010 we are progressing like a snail on heat - excited and determined but very very slow Steveo Re: Hydronic heating Vs On slab heating - running cost 9May 06, 2009 9:57 pm Casa2 My running costs will be virtually zero. But it will cost to get the system . I will be using solar hot water panels to feed a tank that will then connect to the in-slab hydronics. There will be no boost. amuheat Hi All, I work for a company who supply and supply & install electric and Hydronic floor heating systems. If we take a look at 'worse case' running cost scenarios for a home requiring comfort heat during mornings and evenings Hydronic in-Slab Max usage rates for the 13 hour per day, 90 day period totals $1502. (Rates ref: http://www.agl.com.au/home/accountenquiries/Pages In my old house, the gas ducted bill was $400 a quarter (cf gas hydronic at $1502) Ooops! A 30 tube evacuated tube solar HWS can heat about 90L of water to 60 degrees for your solar powered hydronic during the middle of winter. About 0.35c worth of natural gas would do the same thing. Re: Hydronic heating Vs On slab heating - running cost 10May 06, 2009 11:52 pm Steveo Is the math the same for Hyrdronic in Slab versus Hydronic Panels ?? If the total output of all panels in a home equals 17kW, then the math for maximum running costs would be the same. If heat losses, for whatever reason prevent the boiler duty cycling during time of use, the boiler will work continuosly and running costs would be $1502. dymonite69 In my old house, the gas ducted bill was $400 a quarter (cf gas hydronic at $1502) Ooops! :shock: $1502 is based on the assumption the boiler does not duty cycle during times of use due to heat losses, resulting in thermostat set point not being reached. A correctly designed floor heat system installed in a build with good insulation and good heat loss management, with thermostatic control should achieve duty cycles of approx 30-35% every hour. In this instance, the gas hydronic slab as per example should cost between $450-$525 a quarter. Where I have returned to sites with the floor heating running, after a customer has called reporting a fault as they have received a 'high' energy bill (particularly with electric systems), I mostly find one of two conditions: - No furnishings on windows with ambient temperatures one or two degrees below set point on thermostat. In this instance, the heat losses through the exposed windows is greater than the amount of heat being supplied by the floor heat system. As long as the thermostat set point is not reached, the system will draw full load during time of use. - Thermostat set point temperature is set incorrectly. The room is warm, the thermostat registers ambient temperature of 22degrees... on inspection the thermostat is set to 25 or thereabouts. Again, as long as the thermostat set point is not reached, the system will draw full load during time of use. Re: Hydronic heating Vs On slab heating - running cost 11May 07, 2009 1:34 am amuheat $1502 is based on the assumption the boiler does not duty cycle Where I have returned to sites with the floor heating running, after a customer has called reporting a fault as they have received a 'high' energy bill (particularly with electric systems), I mostly find one of two conditions: - No furnishings on windows with ambient temperatures - Thermostat set point temperature is set incorrectly. Thank you for an unbiased and clear commercial disclosure of the real costs of hydronics. I think you have made it clear that the cost of hydronic gas is on par with other central heating systems. As I have commented previously, radiant floor heating is comfortable but unlikely to be cheaper to run than other forms of heating. Your real world experience has confirmed this impression. It is not significantly 'greener' in terms of energy consumption. The argument is not furthered with solar hydronics. No solar HWS can remotely meet the hot water needs of a family in winter let alone drive a hydronic system. Apart from the lack of cost-effectiveness, the embodied energy of the installation is considerable for what is little energy payback. BTW I have heard mixed comments about the extent of slab insulation for radiant floors. Some sources suggest that edge insulation is adequate and other stipulate that the base needs to be insulated as well. Is there any data on the magnitude of benefit from either measure and the additional cost to install this? Re: Hydronic heating Vs On slab heating - running cost 12May 16, 2009 10:14 am Hi all I live in Canberra, and hopefully in a new house this time next year. I will be building in a rural area, and thus no natural gas. If I go Hydronic, I think it will be radiators, and a zoned type arrangement. Reading the various threads on this topic (and it is certainly topical), I think my options are solar, wood or LPG (or a mixture of all). I have read of several successes with Hydronics utilising natural gas, but has anyone had any experience with the above. Solar has been mentioned several times, but always being planned, and I am not sure if anyone is actually, successfully using solar. My other option will be reverse cycle, but still like to idea of hydronic panels. Cheers Michael Re: Hydronic heating Vs On slab heating - running cost 13May 20, 2009 3:41 am Yeah in most instances, response times for Hydronic gas and electric slab is 8 hours, whilst above slab floor heating is 1 hour. Also, it is assumed thermostatic duty cycles of 35-40% are achievable... _________________ Programmable Thermostats Re: Hydronic heating Vs On slab heating - running cost 14May 21, 2009 11:20 pm Hydronic radiators heat up in 15minutes. Our boiler will be used for instaneous hot water as well as the hydronic heating. Re: Hydronic heating Vs On slab heating - running cost 15May 23, 2009 7:27 am re Solar heating - I heard about this house the other day and apparently the heat comming of the water tanks inside the house is effective. One of the tanks is under the kitchen bench and the heat radiats out as you stand at the bench through timer slats that hide the tank. rather neat IMO. It might be open on Solar House day this year too for those in SA. Heating: Two modular rain water tanks are fitted internally and connected to roof mounted solar panels to provide heating. Wooden louvres control the level of heating. A long low, North-facing, sun-catching window heats tiles on the slab and wall cavities that are filled with cement and covered with industrial checker plate. North facing windows are double glazed and others use laminated glass. Heavy curtains & pelmets used throughout. Floor coverings include carpet in bedrooms and plywood floors in main living area to provide warmth and comfort. Cooling: Ceiling fans, high ceilings, heavy curtains, double glazed windows, internal thermal mass including water walls and vented gables combine with deep verandas and external blinds to the West for effective summer cooling. http://www.sustainablehouseday.com/locations/pdfs_no_addresses/SHD%2008%20info%20Aldinga%203.pdf Re: Hydronic heating Vs On slab heating - running cost 16Jun 25, 2009 9:35 pm mickgem21 Solar has been mentioned several times, but always being planned, and I am not sure if anyone is actually, successfully using solar. There are hydronics systems that have been partially solar powered but I don't believe it is all that common. In all the cases I have heard they have been driven by an evacuated tube system. I was reflecting on this today and this seems to be an overcomplicated, over-engineered and expensive solution. Radiant floors need only to be heated to the high-20s deg C to maintain comfortable conditions. Evacuated tubes really come into their own when either the ambient temperature is low or the water needs to be heated to very high temperatures. Flat plates can't compete. However, hydronic radiant heating requires only a modest temperature rise in the water to be effective. Rather than having a highly efficient system with a small collector surface why not just use a cheaper solar pool heater? The collector efficiency is lower but this is compensated for by a large collector area. It will deliver lower temperature water but should provide an adequate amounts of heating energy to keep the slab warm. It's all horses for courses. The solar pool heater delivers more energy for a lower capital investment and with lower maintenance issues. Re: Hydronic heating Vs On slab heating - running cost 17Jun 26, 2009 12:01 am dymonite69 The solar pool heater delivers more energy for a lower capital investment and with lower maintenance issues. so a heatpump would be more feasible and easier to replace; than a pre solar then gas booster setup? however prolly cost more to run? i am also looking to find a way to heat my spa also 2nd-Fix | Blog Building with Desyn Homes previously with the insolvent [url=https://www.facebook.com/7NewsAdelaide/videos/1162546323776021/]Endeavour Homes[/url] Re: Hydronic heating Vs On slab heating - running cost 18Jun 26, 2009 1:49 am FireFox dymonite69 The solar pool heater delivers more energy for a lower capital investment and with lower maintenance issues. so a heatpump would be more feasible and easier to replace; than a pre solar then gas booster setup? however prolly cost more to run? i am also looking to find a way to heat my spa also Judging from comparison tables for hot water systems, natural gas heaters compare favourably with heat pumps in terms of running costs. http://www.sustainability.vic.gov.au/re ... system.pdf To me this suggests that heat pumps are twice as efficient as gas or use half the energy of gas to achieve the same output (gas currently costs half that of electricity). Hooking a heat pump to a hydronic system makes good sense (particularly if you don't have town gas). You can have a solar pre-heater for either a heat pump or gas heater. Just remember that hot water systems run at higher output temps and conventionally this is what is used to run a hydronic system. I am theorising that this is unnecessary. The modest temperature but high heat capacity of a large solar pool collector is all that is required to bring the slab up to a comfortable temperature. Assuming a 50% efficiency of converting solar energy into useful heat then I would estimate that you need a solar pool collector size equal to about 30-40% of the floor area that you wish to heat. My only reservation are the health issues of Legionella growing in your tepid water recirculator. However, if it is a closed system then I can't see why this would be an issue. On the other hand one could intermittently raise the temperature of the water to 60 deg and kill the germs off before they multiply to a significant number. There is some energy cost for this but better than continually heating it to that temperature. Re: Hydronic heating Vs On slab heating - running cost 19Jun 29, 2009 12:53 pm Very interesting inputs. I'm also considering a in-slab system, but the cost really put me off. Then I discovered the in-screed and under carpet electric heating system, and electric oil heating radiators. Still waiting for a quote back. Looks like they both cheaper to install, and has faster reaction time. With the 2kW in-grid solar panels I'm planning to install, hopefully that also bring down the electricity bill. But my concern is, what about the electromagnetic field issue that come with the under floor electric heating system??!? I've heard many comments about the higher risks of cancer related to the electromagnetic, and still researching on this topic. Does anyone know anything about this? I'd really prefer a warm floor, but if that means putting my family's health in risk, then i'd go for the radiator panels. Re: Hydronic heating Vs On slab heating - running cost 20Jun 29, 2009 2:05 pm popcorn-chicken in-screed and under carpet electric heating system, and electric oil heating radiators. With the 2kW in-grid solar panels I'm planning to install, hopefully that also bring down the electricity bill. comments about the higher risks of cancer related to the electromagnetic Any electrical form of heating will always be more expensive (with higher CO2 emissions) than natural gas to run. LPG is the most expensive (but it does burn cleanly). Here are some cost comparisons. http://www.sustainability.vic.gov.au/re ... system.pdf http://www.sedo.wa.gov.au/pages/heat_run.asp If you electric it is best to use off-peak (it is about half the cost and approaches that of natural gas prices). The most efficient electrical heating device is reverse cycled AC. As you can see from the table - peak electricity heating is hideously expensive. Before spending huge $$$ on solar PV panels, consider more effective ways on saving energy e.g. good insulation, weather-seals and getting as much sun into the house. Did you know that a 300L solar hot water system saves as much energy as a 1.5kW PV system? The evidence for the deleterious effects of EMR is yet to be established. Probably because it hard to quantify and the effects may not be seen for years. Harm has been observed in cell studies and extrapolated to human effects. Does anyone have a suggestion for a good hydronic in slab heating speacialist who may be able to help me with an existing system and wether or not it may need a seperator… 0 4870 2 6178 Hi all I am looking to run a water line under my concrete footpath which is directly next to my home, was seeing if this is possible without cutting the entire section… 0 20166 |