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Re: Temperature regulation in radiant floor heat system.
It depends a bit on the garage load. How warm, how tightly do the doors seal. That can be a big load if you are looking to maintain 68- 70F.One way to look at boiler sizing.The house is 20 years old and reasonably high quality with 2x6 exterior walls and high quality windows.
About 25 BTU/ sq ft is about what you can comfortably get from a residential floor. Above that the floors tend to get pretty hot, un-comfortable to walk on.
So 5000 X 25= 125,000 btu/ hr load.
The garage? call it 800 sq ft? 800 X 25= 20,000 btu/hr load. Total load 145,000 btu/ hr.
So a boiler in the 175,000- 180,000 btu/ hr range should cover your application.
Oversizing, grossly over sizing leads to boiler short cycling, lowered boiler efficiency, excessive wear. Not good.
If you have a radiant design, it should spell out the boiler sizing?
New, well insulated, tightly constructed homes could Have loads in the teens maybe single digits as in BTU/ sq ft.
This recently built home up around Utica, NY has a heat load of just over 10 btu/ sq ft.
So a 5000 square foot home could require a 50,000 btu/ hr boiler in this case. A 270K boiler would be near 5X oversized!
So confirm some load numbers before you go way overboard on the boiler sizing.
But without supporting data, I've always thought the 270K boiler was a bit large. And yes, in my observations, it short cycles.
A WAG, that 270 could be twice the size you need.
hot_rod
1
Re: Jal
Were the other 6 homes coal-fired? Or were they fighting against NG with FUD?Oil was much cheaper compared to NG and other fuels then. Most medium duty trucks and some semis were still gasoline. Not as much demand for Diesel.
Pre OPEC, and low transportation costs to ship Oil to the East Coast. Also, NG was not as available on the East Coast as it is today. The other six? Maybe three were electric resistance, and three were coal?
WMno57
1
Re: Runtal Radiator sizing, EK Resolute RT oil boiler
Good comments all around.
Another way to think of it is radiation is always grossly oversized during the shoulder seasons when heat is still required although it’s “warmer” outside. We never really think of that is causing any issues.
You’ll need to have proper circulation and flow, or else the temperature drop through the radiation will be very high and the downstream rooms will not heat as desired. All of this points to proper system design.
The majority of the energy savings come from low mass and thermal purge operation. A small amount of additional savings can be squeezed out with adequate radiation (designed for lower than 120F return temperatures on design day) using a thermal purge condensing boiler, but it is only a few percent more. And the domestic hot water system will need to thermal purge as well or else the boiler will finish hot several times a day (this happens with an indirect tank with an internal coil, thermal purge works well with a heat exchanger).
The majority of the energy savings come from low mass and thermal purge operation. A small amount of additional savings can be squeezed out with adequate radiation (designed for lower than 120F return temperatures on design day) using a thermal purge condensing boiler, but it is only a few percent more. And the domestic hot water system will need to thermal purge as well or else the boiler will finish hot several times a day (this happens with an indirect tank with an internal coil, thermal purge works well with a heat exchanger).
Best,
Roger
Roger
Roger
1
Re: HTP, US Boiler, or Lochinvar?
The Lochinvar's I service seem to hold up longer and without the fussy problems that other boilers have. Failed sensors, ignition control modules, igniters, pressure switches, etc. I think Lochinvar uses quality components. Good technical support as well.
I'd rather buy an expensive boiler that won't have annoying and expensive repair costs.
@mattmia2 said:
I'd rather buy an expensive boiler that won't have annoying and expensive repair costs.
@mattmia2 said:
Look at what you want the controls to do, the lochinvars tend to have more configurability which may or may not matter in your application.
Not something to take lightly or for granted. It can be a big deal to have more control options.
Re: Electric Radiant Snow & Ice Melt System.
@Allislandradiant what brand of mats are those? Maybe you mentioned it, and I didn't see it.
I was only offered the cable as an electric option. I liked the idea of electric radiant driveway. So simple with no pumps, glycol, and very little controls.
I'd be fine spending $20 on electric after I snowblowed to get rid of ice etc. Just doing key areas that are steeply sloped.
I think my wholesaler quoted price/ft² was about what it cost me to lay 2" of asphalt.
I was only offered the cable as an electric option. I liked the idea of electric radiant driveway. So simple with no pumps, glycol, and very little controls.
I'd be fine spending $20 on electric after I snowblowed to get rid of ice etc. Just doing key areas that are steeply sloped.
I think my wholesaler quoted price/ft² was about what it cost me to lay 2" of asphalt.
Re: Nailing the lid on the Suspended Tube Coffin
Same difference
Rob, you, and the radiant market are telling the customer what constitutes comfort. You are telling your customers that radiant floors are more comfortable than a decent radiator system, (for example) but you don't know it to be true. And it's not true.
Radiant floors are not the only way to create a comfortable heating system. That's just hype and hubris that can't be supported.
I tell people that I can produce an equally comfortable, but much more efficient and effective heating system using other, more reliable and effective techniques and we all know that it's true, and if you ask them later, they would tell you that it's true. Are you saying that they are "uncomfortable", or that they would be more comfortable with a cheap and cheesy radiant floor that is so constipated that it may not even be able to produce enough heat at design? I think that they would disagree.
For what it's worth, ASHRAE does define comfort as "that indoor condition at which an occupant expresses satisfaction with the thermal enviroment." They go on to say that different individuals, depending on their health and age and degree of physical activity etc will define comfort in differert ways. Engineers actually only have to "satisfy" 80% of the occupants of a building to be considered legally "successful". It's hard to account for the other 20% or exactly how "uncomfortable" they are.
Again, I notice that no one in this thread is responding to any discussion about performance issues. All I hear are discussions revolving around the raw ability of a heating system to carry design load. THAT IS NOT WHAT I MEAN WHEN I USE THE WORD "PERFORMANCE". I think that's unsophisticated, shallow thinking. You mentioned the possibility of "higher fuel bills". Your customers may be interested in this. This is one of the real measues of performance.
Also, Rob, I doubt very much much whether many folks in this country have much experience with a high performance radiator system. One with generous radiating surface in the room, above the floor and it's thermal resistance, one moving heat by convection directly into the room air, one on full reset that drives the boiler temp down to the lowest possible temp, one that is appropriately zoned to deliver the right amount of heat where and when it's needed, one that may even use proportional TRV's ir eveb proportional zone valves rather than on/off thermostats to provide the final measure of control to regulate space temperature, to provide homeostasis. That's what we are after, homeostasis, or consistant and controllable thermal equilibrium with the lowest possible energy input. That is where "comfort" comes from. The absence of discomfort. Satisfaction with the thermal environment.
We owe it to ourselves, our customers and our environment to carefully define comfort, performance, efficiency, and effectiveness. We're the pro's, it may seem arrogant, but we really do know more about comfort and performance and efficiency than our customers do. We live and breathe this ........ stuff. {private grin} We live with and, (hopefully), learn from our mistakes and improve our methods. Our customers respect us and pay us for our expertise, experience and best advice, just as we respect and pay others for theirs.
Monitor a heating system for a couple of years and evaluate the several numerical variables that constitute performance and then talk to me about comfort. There is much more to this issue that is being ignored and is only revealed to those willing to take a much closer, objective, look. The devil, as they say, is in the details.
Dale
Rob, you, and the radiant market are telling the customer what constitutes comfort. You are telling your customers that radiant floors are more comfortable than a decent radiator system, (for example) but you don't know it to be true. And it's not true.
Radiant floors are not the only way to create a comfortable heating system. That's just hype and hubris that can't be supported.
I tell people that I can produce an equally comfortable, but much more efficient and effective heating system using other, more reliable and effective techniques and we all know that it's true, and if you ask them later, they would tell you that it's true. Are you saying that they are "uncomfortable", or that they would be more comfortable with a cheap and cheesy radiant floor that is so constipated that it may not even be able to produce enough heat at design? I think that they would disagree.
For what it's worth, ASHRAE does define comfort as "that indoor condition at which an occupant expresses satisfaction with the thermal enviroment." They go on to say that different individuals, depending on their health and age and degree of physical activity etc will define comfort in differert ways. Engineers actually only have to "satisfy" 80% of the occupants of a building to be considered legally "successful". It's hard to account for the other 20% or exactly how "uncomfortable" they are.
Again, I notice that no one in this thread is responding to any discussion about performance issues. All I hear are discussions revolving around the raw ability of a heating system to carry design load. THAT IS NOT WHAT I MEAN WHEN I USE THE WORD "PERFORMANCE". I think that's unsophisticated, shallow thinking. You mentioned the possibility of "higher fuel bills". Your customers may be interested in this. This is one of the real measues of performance.
Also, Rob, I doubt very much much whether many folks in this country have much experience with a high performance radiator system. One with generous radiating surface in the room, above the floor and it's thermal resistance, one moving heat by convection directly into the room air, one on full reset that drives the boiler temp down to the lowest possible temp, one that is appropriately zoned to deliver the right amount of heat where and when it's needed, one that may even use proportional TRV's ir eveb proportional zone valves rather than on/off thermostats to provide the final measure of control to regulate space temperature, to provide homeostasis. That's what we are after, homeostasis, or consistant and controllable thermal equilibrium with the lowest possible energy input. That is where "comfort" comes from. The absence of discomfort. Satisfaction with the thermal environment.
We owe it to ourselves, our customers and our environment to carefully define comfort, performance, efficiency, and effectiveness. We're the pro's, it may seem arrogant, but we really do know more about comfort and performance and efficiency than our customers do. We live and breathe this ........ stuff. {private grin} We live with and, (hopefully), learn from our mistakes and improve our methods. Our customers respect us and pay us for our expertise, experience and best advice, just as we respect and pay others for theirs.
Monitor a heating system for a couple of years and evaluate the several numerical variables that constitute performance and then talk to me about comfort. There is much more to this issue that is being ignored and is only revealed to those willing to take a much closer, objective, look. The devil, as they say, is in the details.
Dale
Re: Nailing the lid on the Suspended Tube Coffin
You don't think so?
You think all or even a majority of suspended tube jobs are not heating the homes they are installed in adequately?
Could they be better? Sure. Or they could be baseboard, or FHA. Provided they were properly designed, the suspended tube job is still going to be more comfortable than baseboard, typically, or FHA, most definitely, and more efficient as well.
Fact is, not every job has the budget to do the kind of job we'd all like to do on every job. Sticking to the best is GREAT if you can do it. Not everyone can. Not every job needs to use 120 deg water or lower, not every job needs full indoor feedback and outdoor reset, not every job will even benefit that greatly from using radiant floor. The entire equation needs to be taken into account. Thermofin is top of the heap, no doubt, but there is a whole heap under it that would like to have good heat too!!!
_______________________________
Northeast Radiant Technology, LLC
Robert Brown, Co-Owner
NRTradiant.com
You think all or even a majority of suspended tube jobs are not heating the homes they are installed in adequately?
Could they be better? Sure. Or they could be baseboard, or FHA. Provided they were properly designed, the suspended tube job is still going to be more comfortable than baseboard, typically, or FHA, most definitely, and more efficient as well.
Fact is, not every job has the budget to do the kind of job we'd all like to do on every job. Sticking to the best is GREAT if you can do it. Not everyone can. Not every job needs to use 120 deg water or lower, not every job needs full indoor feedback and outdoor reset, not every job will even benefit that greatly from using radiant floor. The entire equation needs to be taken into account. Thermofin is top of the heap, no doubt, but there is a whole heap under it that would like to have good heat too!!!
_______________________________
Northeast Radiant Technology, LLC
Robert Brown, Co-Owner
NRTradiant.com
Unknown
1
Re: Nailing the lid on the Suspended Tube Coffin
Dale
You are incorrect. The hallmark of radiant is not low water temperature operation. The hallmark is warm, comfortable floors, as far as many end users are concerned.
I wholeheartedly agree that suspended tube sucks, however it does have a place in the radiant professional's "toolbox" of applications. I can count on the fingers of one finger how many times I seriously consider suspended tube for a project in a year, and we implement it even less than that. But it does work, it is cheap, and it does the job it is supposed to do: heat the floors. If proper design is done, of course.
Could it be better? Of course. But then again, if you drive 100 miles a year in your car, it doesn't make sense to pay twice as much for something with twice the gas mileage too. There are economic "balance points" that cannot be ignored.
_______________________________
Northeast Radiant Technology, LLC
You are incorrect. The hallmark of radiant is not low water temperature operation. The hallmark is warm, comfortable floors, as far as many end users are concerned.
I wholeheartedly agree that suspended tube sucks, however it does have a place in the radiant professional's "toolbox" of applications. I can count on the fingers of one finger how many times I seriously consider suspended tube for a project in a year, and we implement it even less than that. But it does work, it is cheap, and it does the job it is supposed to do: heat the floors. If proper design is done, of course.
Could it be better? Of course. But then again, if you drive 100 miles a year in your car, it doesn't make sense to pay twice as much for something with twice the gas mileage too. There are economic "balance points" that cannot be ignored.
_______________________________
Northeast Radiant Technology, LLC
Unknown
1
Re: Runtal Radiator sizing, EK Resolute RT oil boiler
Well, on a heat demand, the zone valves won't open until the boiler reaches I believe 140°. Not positive on that temp but just for arguments sake.
Once the zone valves open, the return temperature sensor monitors that water temperature and adjusts it's output temperature accordingly.
So if the return temperature drops too low, the zone valves will close while the burner continues to heat the water. It might take a few cycles of on/off with the zone valves until the return water temperature rises enough to keep them open.
Once the zone valves open, the return temperature sensor monitors that water temperature and adjusts it's output temperature accordingly.
So if the return temperature drops too low, the zone valves will close while the burner continues to heat the water. It might take a few cycles of on/off with the zone valves until the return water temperature rises enough to keep them open.
HVACNUT
1
Re: Runtal Radiator sizing, EK Resolute RT oil boiler
Wel, as you are aware, a radiator -- any radiator -- has a heating output (power) which is more or less directly proportional to the temperature difference between the radiator and the surroundings. (as the temperature of the radiation gets really high, beyond what we are worried about (I hope!) it's not linear any more but that's a side problem). So... if you have a radiator of a given size, and desire a certain power output, you will then be able to figure out the required size of the radiator. In your thought about the undersized radiator, if you could feed it hotter water it would radiate more -- and you might be warm enough (this is one of the areas where steam to hot water conversions gets people in trouble -- the hot water in the radiator is nowhere near as hot as the steam). Conversely, as you lower the temperature or the water and the radiator, you get less power from a given radiator.
So your bigger radiator needs lower temperature water or you'll be too warm. Now there are basically three ways to do that -- you can lower the average temperature over time, by stopping and starting the flow through the radiator, or you lower the actual temperature of the water by mixing the hot supply with colder return. Or, if the boiler itself can modulate, you can reduce the output temperature of the boiler.
Now for a non-condensing boiler, such as you mention, only the first and second options are possible -- and there is a situation where you can get into difficulty: if the boiler is really too small, it may not be able to deliver enough power to the radiation to keep the return temperature in the operating range, even if you turn it on or off. Without using a buffer tank or mixing valves, the boiler is going to be very unhappy.
So your bigger radiator needs lower temperature water or you'll be too warm. Now there are basically three ways to do that -- you can lower the average temperature over time, by stopping and starting the flow through the radiator, or you lower the actual temperature of the water by mixing the hot supply with colder return. Or, if the boiler itself can modulate, you can reduce the output temperature of the boiler.
Now for a non-condensing boiler, such as you mention, only the first and second options are possible -- and there is a situation where you can get into difficulty: if the boiler is really too small, it may not be able to deliver enough power to the radiation to keep the return temperature in the operating range, even if you turn it on or off. Without using a buffer tank or mixing valves, the boiler is going to be very unhappy.
