low btu/sq ft?

Bob Bona_4

for the info! Interesting how your delta is almost even! Side note, my 3 year old prefers sleeping on the QT floor side of the house. Won't catch him laying on the bb side ;)What is your OD temp there now?

I have a funny feeling that since codes require penetration firestopping these days, we are not getting the overshoot bleed we would see previous. Heat constipation, if you will :)

Bob Bona_4

sumptin' don't sound right

but I just did a MJ calc for that 11K new construction @warmboard, for the HVAC end of things. Just for goofs I checked the loading, and come up w/ a tad under 14 BTU per sq ft. Anyone else seen number like this for new tight construction, R19 walls, R38 foamed ceiling? MJ says 160K BTU needed for 11,450 sq ft. (heat side)

Can this be? Hmm..I was thinking 20-25 roughly, but I want to check w/ you guys...Parameters are 0 out 72 in BTW.

S Ebels

Yep!

The best example I have is the home my son in law and daughter built a couple years ago. R-19 dense pack cellulose in the walls + 1/2" foam + 3" thick log siding. Good windows and doors and R-40+ in the ceilings. In addition the house is wrapped very tightly. I'm edumacationally guessing ACH of .3 without the HRV running. The heat loss (HVAC-CALC) I ran indicated 106,000 BTU @ design, -10*. We selected a Vitodens 8-32 and sized radiators and Climate panel to allow a max boiler temp of 140*.

We've had problems regulating the temp in the house since built. It reacts to lighting and people loads nearly instantly. For example, with normal lighting turned on the place will heat nicely but throw a party,add 15-18 people and turn on all the lights and the place jumps about 5-7* before the floor and rads coast to a stop. I have no doubt that a 6-24 would have been MORE than adequate to heat the place even with no internal gains. I have NEVER seen the 8-32 at full throttle other than during DHW production, including actual design conditions we had the first winter. If a 6-24 is in fact the right size, and I know it would be, that would equate to a load of around 10-12 BTU's/ sq ft.

don_185

I agree

I'm doing one right now with 10 to 12 btus/sqft.I'm also wondering should I be doing wall emitters instead of infloor..just for the reason MR Ebels stated,quicker responce.

Your thoughts?

Mike E_2

The other thing about doing radiant floors in such a low load house is that the floors will never feel warm. The floors will operate just a few degrees above room temperature, and might acutally feel "cool" alot of the time. The customers will probably be disappointed because they spent all the money and effort for radiant floors, but will never feel the "toasty toes".

I would think that panel rads or baseboard would be a better choice for such a structure. Although, if they want to spend the money to get an invisible system, then the radiant floor is still the best choice, just make sure they aren't expecting warm to the touch floors.

Michael

jp_2

keep in mind,

though the floors may seem cool, this would point to the best condensating point, recoupe of heat, thus making this design more efficient than panels/BB.

in a smart control system you could always boost the floor temp at certain times of the day to give those floors a 'warm' feeling. night time set back would be a good example, then warm breakfast time floors.

Nron_13

different floor ing

look at different flooring options and using radiant floors in areas only where they will be for longer periods of time like in the kitchen around the table to allow for higher floor temps to heat the space with less thermal mass the Bean has an artical at his website Healthyheating.com that talks about when working in the super insulated homes

Mark Hunt

Example


We did a radiant system in a 5000 sqft. building. Slab on grade, R-30 walls, R-38 ceilings.

There is a Munchkin T-80 heating the building. That works out to 16 btus/sqft at design day.

Been in operation for two years now.

Mark H

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Bob Bona_4

what

do you use for your in/out temps up there, Mark?

Mark Hunt

Indoor


is 70 degrees with an OD temp of -10.

Many years ago I would have put a 175k boiler in that place.

We are constantly removing old heating systems and replacing them with units that are at least half of what was in there to begin with. Last night I visited a new home(modular) that is approx. 1800 sqft. There is a 147,000 btu input boiler there. 120 feet of baseboard.(All on one zone)

Let's play with numbers. We'll assume 25 btu's/sqft heat loss @ design day. That's 45,000 btus for this home when the OD temp is -10, ID temp @ 70.

120 feet of baseboard x 560 btu's/linear foot = 67,200(There are two toe-kick heaters here as well, figure 4500 each) Grand Total= 76,200.

Boiler has an output of 124,000.(give or take)

The baseboard and toe-kicks were installed by the modular company. They also only dropped one t-stat wire. (Not sure who does there heat loss calcs)

The boiler and indirect were sized by a supply house.

A local plumber put this all together.

Boiler short cycles, house doesn't heat and the HO can't fill his soaker tub without running out of hot water.(Indirect is on priority)

I understand your hesitancy about the low btu/sqft numbers. When so many are putting in monsters, we show up with puppies.

Mark H


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John Ketterman

My area is -15F design. Our 2200sf house is doing fine with a 80,00 BTU Munchkin, and based on usage I expect it to be just fine on a design day. That's 36 BTU/sf. But it's a 1920 BRICK house. (The old boiler was 175,000 BTU.)

In a new house in a 0F design area, 14 BTU/sf doesn't sound low to me. It sounds high. But load calcs always overestimate.

Bob Bona_4

just got

the "spec" sheet. Ready?

"Two WM EG75 boilers with tekmar control (sic)."

300 in/240 out.

600 in/480 out when both on.

Atmospheric 81% non condensers.

I'm coming in with two Triangle Tube Solo 110's-one under each arm.

What weirds me out is my rough estimate of 20-25 per square, putting sizing at around 275K. OK, I think, sounds reasonable..

Bob Bona_4

and

how often are 11 zones of hydro and 22 zones of radiant gonna call at the same time?

S Ebels

Hey Bob

I just got back from the kid's house, checking to see where their heating curves and temps were at for you. As I posted above they have a Vitodens 8-32 running about 1,600 sq ft of Climate Panel (circuit , thirteen assorted radiators and an infloor slab in the basement run off a secondary mix valve slaved to the ranel rads.

The curves are currently set thusly:

Circuit A, radiators 1.1 curve with a shift of +3*C
water temp in that circuit is running 103-109*

Circuit B, Climate Panel, .3 curve with a shift of +4*C water temp is running a steady 79* with the floors sitting at 74-75* on the tile and the wood

Slab circuit for basement, supply water temp at 72* and the slab is running 71. (more or less constant circ with a relay/thermostat cycling the pump off when needed)

Air temp in the morning is about 68-70 and by this time of day it's crowding 74-75. Too hot for my son in law which is why I was over there. (Well, that and it was a good excuse to play a game of ping pong with my daughter and pester the grankids)

The rads all have TRV's and they were basically shut down except for the bonus room over the unheated garage. I've been trying to get the system adjusted to the point where the floors are not quite keeping up, thereby allowing the rads to act as the "thermostat" for the house. So far this winter (1st since the house was totally completed) we've been astounded at how little heat it takes to keep the place warm and how little additional heat it takes to really raise the indoor temp. If Sue goes on a baking binge (I love it when she does that) and has the oven on for a good share of the day, the rads will shut down and the floor alone will ratchet the temp up faster than you can say "IT"S HOT IN HERE"!!

In retrospect, I think that I would have incorporated a wall thermostat on each zone which would control the corresponding circ. This would allow instant shut down of the "heat" as soon as the indoor temp got past the set point. That kind of goes against my "religion" but these tight houses are demanding in a different sort of way than we are used to. As of right now the only control for the house is the TRV's on the rads. The floor is constant circ and water temp is reset via motorized Viessmann mix valve.

So I guess waht I'm saying is, trust your heat loss calc to err on the high side and don't be surprised at what you see in terms of btu/ sq ft. Also, find some way to incorporate a "heat limit" device that will provide positive shut down of the heating system when indoor conditions warrant.

S Ebels

Forgot that

OD temp is currently 33*. Also, if you're familiar with the Vitodens, the Day/Night dials are set at 65 and 58 respectively. I haven't had a satisfactory answer yet regarding the function of those dials but from how this system works, they appear to change the whole algorithym (sp) of the control. Some day I'll get Jim McCarthy on the phone and pick his brain........

Rollie Peck

Vitodens Day/Night dials

Hi S Ebels:

I have a Viessman controller atop a 4-way valve on my

system. It has a built-in night time setback and the dials

determine what temperature you want the system to shoot for

during the day and during the night. The times are also

adjustable and the default times are 10PM and 6AM.

I have the daytime dial set for 75 degrees because my

wife's basement workshop needs heat when the outside temp-

erature is 65 degrees. The controller shuts down the

secondary pump when the outside temperature reaches the

daytime temperature you set.

I have the night temperature set to 60 degrees, but

notice very little drop in the house temperature, probably

because we have upgraded the windows and insulation and

installed masonry tile in the bathroom, kitchen and central

hallway.

Rollie Peck

Homeowner

hr

It doesn't matter what type of contro(s)

you have on the heating system if the overshoot is caused by lighting, cooking, refer heat rejection, and or people load. The space will overheat in super-insulated homes regardless of the heat emitters.

I've been wondering if a variable speed air handler that has an economizer to allow some outside air to blend in may be the only quick temperature "adjuster"

The heat, or "overheat" regardless of the source, just doesn't leave those "foamblock" superinsulated homes.

I think th IAQ becomes a much bigger issue than the heat loads.

A "too warm" stale aired home! What have we created?

hot rod

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jp_2

totally agree hot rod!

no 'heat controller' can anticipate that turkey cooking all day or the sunny winter day. thats why there NEEDS to be indoor feedback, at least the boiler can shut down at the dinner party. boy sounds like the need for zones too.

fresh air circulation systems are great for this.

Unknown

depends on how well you balance water temperature requirements with flow and emitter sizing, and how well you set the reset curves

S Ebels

Hot Rod

I think that a combo system of radiant, be that floors, walls, ceilings or rads along with an air handler would be the Holy Grail of the residential HVAC world.

The problem is, at least as far as my product knowledge extends, no manufacturer makes a one piece, integrated air handler that incorporated heating, cooling, ventilating and outside air (economizer cooling). A person can field fabricate something like that using a good air handler like LifeBreath's HRV/hydronic furnace combo but then you're faced with something homemade as far as the "economizer" dampers and controls. I played the around with the idea using LifeBreath's CAF (clean air furnace) trying to do just that but by the time I had added up the $$.$$ for all the controls and motorized dampers it had a pretty healthy price tag.

I'd really love to see one of our hydronic manufacturers pour some research and engineering dollars into designing such a beast. It would satify a host of needs that are presented by new, tight structures. I think something like that, driven with a mod/con boiler could reinvent how we do heating/cooling in this country.

Gordy

What have homeowners become?


Fellas, I'm just a homeowner absorbing information on this site. Almost all of the discussions are very interesting as this one.

The idea of sealing ourselves into our own byproducts with these super tight homes has concerned me also. We do it in the name of conservation, and we as homeowners/contractors have had to become ever more controlling of our enviroment.

The last few threads about being able to control latent loads in super tight homes presents some interesting avenues for development of controls, and systems. There will be a market for this.

I myself tend to be simplistic about a homes function. To me a highly technological enviromental control system, Can be a little over bearing for some, to most homeowners that look to purchase a home, I myself excluded from that statement.

I love the ideas, and work that I have viewed on this site. but one has to keep in mind that if I sell my home is this type of system / systems going to be a turn off to some buyers.

As far as controling latent heat loads what ever happened to opening a window for a while. Have we as the average homeowner become that lazy or what? Are we as people that fragile to need such a controled enviroment? A window is even adjustable little open or all the way.

I realise that with the tight home craze to ever decrease our carbon foot print on mother earth, has created certain areas (HVAC) that need special attention with in the home.


Before you guys lop my head off I'm not criticizing your ideas, or work. They are top notch, and forward thinking to solve problems the average person does not realise are created with that energy efficient home they want. You are all the ones that make that enviroment a safer place.

Sorry so long winded my statements may not apply to this thread, but I think radiant will be losing its luster with these super insulated low load homes. Why would someone want to spend the extra dollars for a top notch hydronics system when they can almost heat there home with latent loads. Something to ponder.


Gordy

Unknown

You've got some points gordy. but some counter point, for you:

-opening a window is not comfortable, it's not efficient, and it requires a homeowner to NOTICE THEIR ENVIRONMENT. do you have any idea how many people out there are living with asthma, stuffy noses, sick days, etc and never make the connection with their air quality? I would say it's far more common than you think. I see it with people even AFTER they are told what's going on!

-as for full fledged radiant floors, I agree, the tighter the envelope, the less relevant they become.. to a point. Barring some major changes in how we build though, and by that I mean serious increases in insulation levels, or massive changes to earth sheltered building, something like that.. something hydronic and low temp (perhaps radiant ceilings, panel radiators) has a major appeal; anything that can heat water even a little bit could potentially heat the home. That is, every energy source on the planet.

Flexibility in this changing world is pretty attractive, I think, and top notch hydronics don't HAVE to break the bank.

Gordy

> You've got some points gordy. but some counter

> point, for you:

>

> -opening a window is not

> comfortable, it's not efficient, and it requires

> a homeowner to NOTICE THEIR ENVIRONMENT. do you

> have any idea how many people out there are

> living with asthma, stuffy noses, sick days, etc

> and never make the connection with their air

> quality? I would say it's far more common than

> you think. I see it with people even AFTER they

> are told what's going on!

>

> -as for full

> fledged radiant floors, I agree, the tighter the

> envelope, the less relevant they become.. to a

> point. Barring some major changes in how we

> build though, and by that I mean serious

> increases in insulation levels, or massive

> changes to earth sheltered building, something

> like that.. something hydronic and low temp

> (perhaps radiant ceilings, panel radiators) has a

> major appeal; anything that can heat water even

> a little bit could potentially heat the home.

> That is, every energy source on the

> planet.

>

> Flexibility in this changing world is

> pretty attractive, I think, and top notch

> hydronics don't HAVE to break the bank.

Gordy

Well Rob Lets look at where the bulk of the latent heat and humidity comes from. Kitchens, Laundry Bathrooms, and the exceptionally over lighted rooms in a home.

If you really want to have a hands off control system then each of these potential problematic rooms would have to be linked to a hrv or variable speed air handler plus boiler. Which would be zoned for each area. Controlled by sensors that could "anticipate" the usage of ovens, showers, baths, laundry, lighting etc. If you key on the t-stat you would be behind the ball as far as getting a handle on the latent heat before it increases the temp in the room.

To "anticipate" the usage you would need to be linked to the electrical on the oven, dryer if applies, and lighting so the hrv or whatever can sense that a latent load event is going to happen. The same would apply to your hot water usage for showers, baths, and laundry. A sensor could be run to the main hot water supply to sense anticipated a latent hot water load event.

Now you have to bring all these sensors together with a control that can desifer how long the sensed usage needs to take place before it disrupts the controlled environment of the room. After desifering the event it will have to relay to shut down the zone for heat activate the air handler, and set a determined rate of fresh air to counter the load.

Sounds very doable but what is the cost? Is it really that necessary to most people?

I agree Rob that there are a whole host of ailments that are cause by tight houses that people don't realize that is the cause living in an out gassing environment with no ventilation. Mold, gasses, stale air along with others have brought on new challenges for you guys with these tight homes.

Can radiant be a part of it as a heating solution that is low cost. I agree 100%,but the average homeowner says Hey I got all this duct work anyway.... So why go with hydronics when all I need is a lower costing furnace to go with the duct work. Your telling me I probably won't have warm floors anyway because of my low load to begin with so why should I opt for the radiant.

Your counter points are well taken Rob I'm just being the devils advocate here.


Gordy

Gordy

Well Rob Lets look at where the bulk of the latent heat and humidity comes from. Kitchens, Laundry Bathrooms, and the exceptionally over lighted rooms in a home.

If you really want to have a hands off control system then each of these potential problematic rooms would have to be linked to a hrv or variable speed air handler plus boiler. Which would be zoned for each area. Controlled by sensors that could "anticipate" the usage of ovens, showers, baths, laundry, lighting etc. If you key on the t-stat you would be behind the ball as far as getting a handle on the latent heat before it increases the temp in the room.

To "anticipate" the usage you would need to be linked to the electrical on the oven, dryer if applies, and lighting so the hrv or whatever can sense that a latent load event is going to happen. The same would apply to your hot water usage for showers, baths, and laundry. A sensor could be run to the main hot water supply to sense a anticipated latent hot water load event.

Now you have to bring all these sensors together with a control that can desifer how long the sensed usage needs to take place before it disrupts the controlled environment of the room. After desifering the event it will have to relay to shut down the zone for heat activate the air handler, and set a determined rate of fresh air to counter the load.

Sounds very doable but what is the cost? Is it really that necessary to most people?

I agree Rob that there are a whole host of ailments that are cause by tight houses that people don't realize that its the cause of living in an out gassing environment with no ventilation. Mold, gasses, stale air along with others have brought on new challenges for you guys with these tight homes.

Can radiant be a part of it as a heating solution that is low cost. I agree 100%,but the average homeowner says Hey I got all this duct work anyway.... So why go with hydronics when all I need is a lower costing furnace to go with the duct work. Your telling me I probably won't have warm floors anyway because of my low load to begin with so why should I opt for the radiant.

Your counter points are well taken Rob I'm just being the devils advocate here.


Gordy

Unknown

I don't think you have to anticipate, unless you're using a high mass emitter. A small amount of temperature swing is ok, more is ok in bathrooms, for instance. Low mass emitters of any kind can respond fairly quickly if you are zoned properly, which doesn't necessarily mean a zone per room or anything like it... think of all the kitchens that are open to a larger space, for example. A good thermostat is under most conditions quite adequate.

Humidity or CO2 sensors can be quite adequate for the air system.

Skip the warm floors.. go radiant ceiling The cost is not much more than baseboard. If your loads are low enough, heating your house with 90 degree solar is pretty sweet!

The other option is to build a loose house (and, relatively speaking, pay through the nose for heating/cooling) with less comfort, or build a tight one and control your environment. That's it.

Now, I grew up in a house that had a FHA system in it, but we used it for about a half hour in the morning and that was it. Otherwise, we heated with a wood stove. It was freezing in the morning, a loose old farmhouse, and we were used to it.

Is that ok? I guess it depends. Until you are truly comfortable in your environment, it's hard to explain how different it is. For me, it's as simple as my wife not being afraid to throw off the covers once in awhile for... uh, no apparent reason.. ahem...

In other words, PRICELESS

Bob Bona_4

now

you're talking Steve. Cold weather shut down on the compressor and economizer action/preheat. Just about everybody has auto changeover stats these days. I suppose the preheat via hydro coil can be modulate based on the ODT and air sensors.

Come to think of it, an interface with the humongo Viking stove hoods would be sweet!

Gordy

LOL !

Yup your right Rob, how far we have came in being creatures of comfort. It does have its benifits as you stated ;D

I gues sometimes I tend to want to keep it simple but we as people are tending to out grow that. I think sometimes it may be done because it can be not because it has to. Not in this particular discussion though.

Just about anything can be done. Look at Bill Gates's castle, and his HVAC set up, anyone know who designed it besides his input, and software design for it. He probably thought it was novel at the time a one of a kind with out a demand for such an enviroment. Little does he know how important it will be..... or maybe he does. Microsoft home enviroment software comming soon to stores near you. Plug, and play sensors controlers ect.


Gordy

John L

Take a look

at this site http://nu-airventilation.com/Enerboss_files/
Armoury%20Square%20Info%20PKG.pdf, it may be something close to what you are thinking of.

John L.

Constantin

Hi Gordy!

You make some very valid points. For sure, as we tighten up our houses, the chance of stale air and all that goes up. It means we have to pay more attention to how we ventilate, how air is exchanged, etc.

Our house has an infiltration rating of 0.2 ACH. I supplement that with 2 TRVs that run for 20 minutes aevery hour on the lowest (and most efficient) setting. Lastly, I also have the air handler turn on and run at 30% speed for 20 minutes on the hour.

Currently, there are only two of us and a cat, but the house doesn't start to become stale even when we have lots of guests over. I believe it's the combination of using the air handler to circulate air throughout the house and the Lifebreath units to bring in new air that makes it possible.

In an ideal world, these sorts of things would come in an integrated package as Steve points out. But few manufacturers cover the scope needed to have one interface for all their equipment. The infinity system from carrier is very interesting and may (some day) be integrated into the carrier-branded HRV/ERV product as well.

Mike T., Swampeast MO

Steve

I've been trying to get the system adjusted to the point where the floors are not quite keeping up, thereby allowing the rads to act as the "thermostat" for the house.

Here's how you should be able to do it:

Use the timer program to put ONLY the underfloor circuit (circuit "B" I presume) into reduced mode (moon dial setting) during the day when occupation/solar gains cause the space to overheat.

Given your observations, I'd suggest a moon dial setting of about 58°F to start.

p.s.

I'd also consider increasing the sun dial setting to 68°F and reducing the shift of BOTH heating curves by 2°C.

rb_6