"Hydronic Heating for Low Energy Houses" by John Siegenthaler

Daox · 11-16-15, 01:36 PM

Here is a nice presentation done by John Siegenthaler (THE hydronics guy, at least in the US). It goes over the basics of a low energy house, passive house is mentioned, then he gets into hydronics, more specifically low temp heated floors and low mass heaters, and much more. He includes a link to a site that will help you size a flat plate heat exchanger (Flatplateselect.com). There are TONS of pictures and info in this pdf. Great for getting ideas and learning the basics of hydronic heating.

Hydronic Heating for Low Energy Houses by John Siegenthaler

MN Renovator · 11-16-15, 04:37 PM

The radiant ceiling of the floor of a 1.5 story makes me shudder a bit. Hopefully there is plenty of air sealing and insulation behind the walls and ceiling of that place or that's a pile of heat getting ejected. I prefer my own heating/cooling not be directly facing or touching a surface where the opposite side is outside the building envelope, the delta T is high enough already.

..personal rant aside. I like these ECM circulators. By the way, the Flat Plate Select link requires a login.

I'm still trying to figure out why the argument for air vs. water always turns to pictures of flex duct and giant chunks of cut out floor joists. If a house has a basement, the ductwork can be installed below the floor joists, that's how ductwork is installed in my house. This also allows for plumbing to be run in the same plane so no penetrations to the floor joists are needed. ..although apparently the electrical contractor opted to drill for the romex. There is no need for large ductwork, a 40k BTUhr 1.5 ton setup would need 600 CFM. Run a trunk box in 4 directions with a decent design using short runs because you don't need to blow air past good windows used in an energy efficient house, only energy inefficient windows. I think the real question is why would you do this anyway, the natural gas connection fee will cost more than the electricity used by air source mini-split heat pumps and a heat pump water heater. ..if the hot water usage is low and you've got low flow heads(1.5 or less gpm such as Niagara Earth) an instant on-demand electric system might even fit the bill without the high initial cost of a HP hot water tank.

It seems to me that hydronic design and implementation is still heavy on labor, in the case of in-floor, ceiling, or other 'wind it all over the house' systems you've got a needlessly complicated system for a house that barely needs heat. A house with a 10,000BTUhr heat load shouldn't need this, your feet won't feel consistently warmer outside of design conditions(and maybe even in design conditions) because if they were, you'd have so much heat coming from the floor that you'd be turning the thermostat down or boiling yourself out.

I think simplicity should be the name of the game. Say you've got a 2000 sq ft foot house with 5BTUhr/sq ft, which is 10,000 BTUhr. You've got 3 bedrooms in close proximity on one side of the house and a living room on another, you could have two 9k mini-splits and that would be oversized. If you really want tight control of the temperature, you could go with 4 zones but I'm thinking this is overkill.

As a personal aside, I've got my house with manual J calcs after I complete my insulation/air seal retrofit down to 10k for 2100 sq ft. If I keep natural gas, I'm going to replace the water heater with a power vent condensing unit and then take the existing HVAC system and plumb a hydronic water coil into it sized to pull no more than 20k BTUhr from the water tank. Thermostat kicks on and the pump from the water tank and the blower kick on. Not too efficient electrically but it won't need to run much and the cost to implement is very low. Most likely I'll be ditching the natural gas though, they keep raising the fixed fee. If I remember right, they are pushing the public utilities commission for $15/month. $180 will be more than the amount I'd spend on heating water and air electrically post retrofit. I'd miss the gas stove, but not that much.

stevehull · 11-16-15, 04:46 PM

Here in the south we need air conditioning. This is not a defect in the southern character - when it gets DAMN hot, you need a place to cool off.

And this means forces cool air through a duct system. I know, I know, a small pipe can carry 1000 times more "cooth" than a similar sized air duct. But the problem is that we also have humidity.

Combine a very nice cool floor (or wall, or ceiling) with a air dewpoint only a few degrees higher and you have condensation. Not good.

Radiant flooring is still to die for in the winter . . . . can we have both without breaking the bank?

Steve

MN Renovator · 11-16-15, 05:18 PM

Quote:

Originally Posted by stevehull

And this means forces cool air through a duct system. I know, I know, a small pipe can carry 1000 times more "cooth" than a similar sized air duct. But the problem is that we also have humidity.

Combine a very nice cool floor (or wall, or ceiling) with a air dewpoint only a few degrees higher and you have condensation. Not good.

Radiant flooring is still to die for in the winter . . . . can we have both without breaking the bank?

Steve

Some of the most efficient inverter ductless mini-split systems would be ideal for Oklahoma. Limit solar exposure in the building design to reduce heating from the sun in the summer, build to R30 walls(ideally), R60 attic, insulated floor, etc. or at the very least R21 with 2 foot on center 2x6 advanced frame construction. Install good windows with thermal performance in mind. With R30, limited solar exposure, and a decent open space building design, put a 9k mini-split in each bedroom(or with a multi-split you have 5k indoor head options) and one in the kitchen/living room space and you could have high 20 SEER, some units touching a hair over 30 SEER. In the winter, these will be barely running with R30 walls and design temperatures in the teens and more than enough cooling in the summer.

Drake · 11-18-15, 09:00 PM

A lot of excellent information on what I have seen as seen as a disconnect from the want of an energy frugal home - a matched frugal HVAC system. Though the distribution systems discussed more efficient for a low demand house they still seem too much 20th century as categorized. The rest of the world seem to be the ones stepping into the 21st. When can we join them?

Am I taking it correctly from the FLIR pics of the radiant ceiling/walls that the supply temp of water is approx 90-95 degrees?

11-16-15, 01:36 PM	#1
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	"Hydronic Heating for Low Energy Houses" by John Siegenthaler Here is a nice presentation done by John Siegenthaler (THE hydronics guy, at least in the US). It goes over the basics of a low energy house, passive house is mentioned, then he gets into hydronics, more specifically low temp heated floors and low mass heaters, and much more. He includes a link to a site that will help you size a flat plate heat exchanger (Flatplateselect.com). There are TONS of pictures and info in this pdf. Great for getting ideas and learning the basics of hydronic heating. Hydronic Heating for Low Energy Houses by John Siegenthaler Attached Thumbnails __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

11-16-15, 04:46 PM	#3
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Here in the south we need air conditioning. This is not a defect in the southern character - when it gets DAMN hot, you need a place to cool off. And this means forces cool air through a duct system. I know, I know, a small pipe can carry 1000 times more "cooth" than a similar sized air duct. But the problem is that we also have humidity. Combine a very nice cool floor (or wall, or ceiling) with a air dewpoint only a few degrees higher and you have condensation. Not good. Radiant flooring is still to die for in the winter . . . . can we have both without breaking the bank? Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

11-16-15, 04:37 PM	#2
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 940 Thanks: 41 Thanked 117 Times in 91 Posts	The radiant ceiling of the floor of a 1.5 story makes me shudder a bit. Hopefully there is plenty of air sealing and insulation behind the walls and ceiling of that place or that's a pile of heat getting ejected. I prefer my own heating/cooling not be directly facing or touching a surface where the opposite side is outside the building envelope, the delta T is high enough already. ..personal rant aside. I like these ECM circulators. By the way, the Flat Plate Select link requires a login. I'm still trying to figure out why the argument for air vs. water always turns to pictures of flex duct and giant chunks of cut out floor joists. If a house has a basement, the ductwork can be installed below the floor joists, that's how ductwork is installed in my house. This also allows for plumbing to be run in the same plane so no penetrations to the floor joists are needed. ..although apparently the electrical contractor opted to drill for the romex. There is no need for large ductwork, a 40k BTUhr 1.5 ton setup would need 600 CFM. Run a trunk box in 4 directions with a decent design using short runs because you don't need to blow air past good windows used in an energy efficient house, only energy inefficient windows. I think the real question is why would you do this anyway, the natural gas connection fee will cost more than the electricity used by air source mini-split heat pumps and a heat pump water heater. ..if the hot water usage is low and you've got low flow heads(1.5 or less gpm such as Niagara Earth) an instant on-demand electric system might even fit the bill without the high initial cost of a HP hot water tank. It seems to me that hydronic design and implementation is still heavy on labor, in the case of in-floor, ceiling, or other 'wind it all over the house' systems you've got a needlessly complicated system for a house that barely needs heat. A house with a 10,000BTUhr heat load shouldn't need this, your feet won't feel consistently warmer outside of design conditions(and maybe even in design conditions) because if they were, you'd have so much heat coming from the floor that you'd be turning the thermostat down or boiling yourself out. I think simplicity should be the name of the game. Say you've got a 2000 sq ft foot house with 5BTUhr/sq ft, which is 10,000 BTUhr. You've got 3 bedrooms in close proximity on one side of the house and a living room on another, you could have two 9k mini-splits and that would be oversized. If you really want tight control of the temperature, you could go with 4 zones but I'm thinking this is overkill. As a personal aside, I've got my house with manual J calcs after I complete my insulation/air seal retrofit down to 10k for 2100 sq ft. If I keep natural gas, I'm going to replace the water heater with a power vent condensing unit and then take the existing HVAC system and plumb a hydronic water coil into it sized to pull no more than 20k BTUhr from the water tank. Thermostat kicks on and the pump from the water tank and the blower kick on. Not too efficient electrically but it won't need to run much and the cost to implement is very low. Most likely I'll be ditching the natural gas though, they keep raising the fixed fee. If I remember right, they are pushing the public utilities commission for $15/month. $180 will be more than the amount I'd spend on heating water and air electrically post retrofit. I'd miss the gas stove, but not that much.

11-18-15, 09:00 PM	#5
Drake DIY Guy Join Date: Jan 2011 Location: Mpls,MN Posts: 315 Thanks: 2 Thanked 17 Times in 17 Posts	A lot of excellent information on what I have seen as seen as a disconnect from the want of an energy frugal home - a matched frugal HVAC system. Though the distribution systems discussed more efficient for a low demand house they still seem too much 20th century as categorized. The rest of the world seem to be the ones stepping into the 21st. When can we join them? Am I taking it correctly from the FLIR pics of the radiant ceiling/walls that the supply temp of water is approx 90-95 degrees?