Super energy efficient home

hot_rod

seems I've been hearing that circ will be on the shelves in a month or two for at least a year now :) Wasn't the distribution price list released when we were at the Foothills Conference with the actual pumps a week or two behind? What happened?

Indications are Wilo will be first to market in the small sizes. Time will tell if being first to market will be a win?

If indeed the sticker price has a comma I hope they don't bring in a boatload of them. A 10 gpm circ that cost half as much as a boiler better have an i-pod built in if it is to sell here.

hot rod

MAQ Crook

Super energy efficient home

My 4132 sf house is so energy efficent that our radiant floor with DHW heating system with a LP munchkin boiler is double the size required. This has caused it to short cycle and conflicts with the DHW indirect(domestic hot water)causing it to fault out. This has been a problem for two + years since installation and I have had all the top experts out to resolve the problem. These top piping experts and manufacturer reps have had me tear the system apart three times. I think that the energy efficient equipment is not designed for a super energy efficient thermal package(Ecobuilt)like mine and thus it does not operate properly. My Ecobuilt homes use 1/2 to 1/10 th the energy of regular house built to code. Anyone out there who can build or design a heating system with radiant for a 4,000 sf house with a heat gain/ loss that needs 29,000 BTUH? Should I split the system with the DHW? I was thinking of using a tankless demand hot water heater for the two separate systems DHW and for radiant heating.

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Paul Pollets

Questions...

Are you using the smallest Munchkin (T50)? If you had to tear the system apart 3 times, I'd suspect piping errors not to mention oversizing of the boiler....I presume this is a DIY project??? You may want to consider a buffer tank.

I have a similar home, (same size home and heat loss) using a Viessmann Vitodens 6/24 with no problems. The system uses an indirect DHWT. The boiler tends to sit at lowest modulation, unless the DHWT requires recovery.

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Constantin

I agree...

29kBTU heatloss is great, but shouldn't be a problem for a small mod-con. At worst, add a buffer tank for the thing to run for longer cycle times. Which model did you install and was the model installed to manufacturers specifications? Munchkins, like many boilers, have very specific installation instructions for good reason.

Mike T., Swampeast MO

I recently faced just that challenge and came up with three possibilities:

In order of increasing cost/complexity:

1) Use a Bradford-White Combi-Core "water heater". It's essentially a standard tank-type water heater with a large diamater HX coil running around the perimeter of the tank. It starts about 1/4 of the way up the tank and continues nearly to the top. I could find no similar product on the market, as others that are "sort of like it" tend to have a rather small HX confined to the bottom portion of the tank.

2) Use a mod-con with a large, dual-coil indirect. Bottom coil to heat the DHW in the tank, upper coil to extract your space heat.

3) Use a mod-con with two separate indirects--one for DHW, the other for space heating. While I believe it would be preferrable to heat the water itself in the indirect used for space heating, you really need a HX arrangement similar to the Bradford-White to ensure efficient extraction of heat from the entire tank.

Since your minimum possible space heating supply temp in the first two cases is the minimum possible DHW supply temp, you'll almost certainly need to use a mixing valve--preferrably reset controlled--for radiant floors. Depending on the mod-con, controlling the third choice could become a nightmare.

Granted the first choice has the lowest heat source efficiency, but no currently available mod-con (they're all too large) is going to perform to its efficiency potential.

When you're using little energy to begin with--think annual space heating consumption more like that of one really cold month for "typical" systems--chasing after another 20%-25% savings at HIGH cost becomes incresingly fruitless.

hot_rod

Even with any of these \"fixes\"

expect to discover that the floor heat may not run all that often. More and more we are seeing super efficient homes being "heated' by the internal gains from appliances, lighting, people, pets, passive solar, etc.

Cool floors is the biggest challange I face with "foam homes"

The problems you mentioned are probably not equipment related but more installation or lack of a good "logic" to make it all work, both piping and control wise. A true expert should be able to troubleshoot, document, and design an acceptable fix for most any radiant problem.

hot rod

Mike T., Swampeast MO

Radiant floors weren't used--I'm actually glad...

Uni R_2

In order of increasing cost/complexity:

0) Use a Prestige sized to the hot water demand.


1) Use a Bradford-White Combi-Core "water heater".

2) Use a mod-con with a large, dual-coil indirect.

3) Use a mod-con with two separate indirects--one for DHW, the other for space heating.

***** ***** ***** ***** *****

Dennis,

My heat load is under 40 MBH, and my Prestige boiler actually only modulates down to 38K input (not 30K as advertised). It's all one zone, soon to have a separate zone option for a pex and plate radiant floor in the kitchen.

No short cycling issues at all as a single zone - very strong arguments for TRV/FHVs. Anyway, I actually feel sinful for the fact that my fan speed has to go at 5300 rpm to heat the water. We got by for the past 7 years on a 46 gallon 3.8 KW electric. I'm really thinking that owners should be able to dial it down to 50 MBH instead of 100 MBH. The recovery would be a user adjustable option. Seems obvious with modulating boilers unless they truly only need to make hot water at full bore.

Anyway, unless you are truly micro-loaded I can't see any downsides to the Prestige, well except prestige. This machine can definitely do a good job of heating light loads - it fires 10 minutes at a time and then rests until it needs to do it again. Nothing wrong with balancing comfort to the duty cycle using that formula. Ten minute firing cycles are long enough to reduce wear and tear and unless a single zone can't handle handle absorbing 7 KBTU in a 10 minute period, there is a model small enough not to short-cycle.

Mark Eatherton

Are we overselling radiant floors??

Don't get me wrong, I LOVE mine, but if our job is to deliver "comfort", and the floors are not warm, are we NOT doing our job?

This controversial issue popped up here not too long ago. If a house is well built, and properly insulated, the floors would NOT be cold, even if they DON'T have heat in them.

I have an "omni directional" radiant panel in the ceiling of my basement office. It heats the basement AND the living room above it, by design (omitted insulation). The floor heat for the living room is really not necessary because there is a panel radiator up there capable of carrying the load by itself. So, it basically is floor conditioning at that point. More importantly, the basement floor in my office is really not cold compared to the core basement located hallway that has NO heat, right next to the mechanical room.

I'm thinking maybe we have marketed these "comfort systems" incorrectly, and the consumer EXPECTS their floors to be warm ALL the time, regardless of the need for heat. I'm thinking we are doing a poor job of educating the consumer. I'm thinking we should be telling them that when it gets REAL cold outside, they MIGHT expect their floors to be warmer than usual, but that if they are generally COMFORTable, that the floors won't be warm...

Funny what we as humans get addicted to eh...

ME

Gordy

ME

Makes valid point about these super insulated homes. Save the radiant floors for the baths,a tiled kitchen, and the basement floor. Use radiant ceiling, walls, and oh yeah windows to cover the rest. If people don't have the radiant floors they won't be disappointed the floor is neutral in temp.

These super insulated houses are going to experience what is similar to a shoulder season in an average insulated radiant home such as mine. You really don't notice an above neutral temp floor until it gets down in the consistant low 20's. I suspect a super insulated foam home would be experiencing this shoulder season at far lower temps than your average insulated radiant home.

Time to look at alternatives


Gordy

Tim_41

Agree with ME

I am slowly redoing our heat system. I first had to reinsulate the 3 out side walls (foam) and some of the roof. Its a wacky house from the 1800's. I have radiant on the 1st floor. After the foam and other improvements, I wish I had just gone with all rads a few years ago. The floor is staying "cooler" because of the renovations. Once the rads are installed for newly gained living space, we'll see what happens.

hot_rod

super insulated SLAB homes

are the tough one for me. Nothing beats a warm concrete floor. But not at the cost of an over-heated, hard to control room temperature.

Even a concrete floor at 72F will feel cold, at least cool to the bare foot(ed) That's where I am struggling. Slab on grade jobs are becoming more and more common with the ICF and SIP methods gaining popularity here.

Having just finished my first panel radiator job, I can see how a nice TRVed panel system could certainly be a replacement in bedrooms and other non-gathering areas.

Perhaps panel rads blended with wider floor loops in kitchen and bath areas, or delete the exterior radiant floor loops as Mark has mentioned a few times, with tighter tube spacing under the traffic and sitting areas?

Time to start re-thinking radiant floor panels design, installation, and control. But I not ready to abandon them completely.

hot rod

MAQ Crook

Real trouble shooter for Radiant/ Super insulated home

The problem is I had Wes from Wirsbo and Dennis S. from Munchkin who is also their design expert come to common design together. Once I had a buffer tank and then on the third design it was taken out again. Once I take out the DHW heater indirect it seems to function fine but I still have not found a true expert who designs for super insulated houses with equipment designed for an even temp. At day time I get alot of solar heat and the equipment gets cold. After the sun goes down the temp finally drops by about 10:00 pm ( no sun it drops at 8:00 pm) anyway by the time it comes up to thermostat setting it is around 12:00 midnight. By morning we are suffering from the radiating heat from the system heating up shutting off and then continuing until it is colled off from firing up. I can heat fine in winter with just a halogen light on in the living room when the whole system goes down. WHO really is an expert as you said for this type of situation?
Thanks for all your feedback.
Dennis MAQ Crook

Mark Eatherton

Sounds like a WHOLE bunch of problems...

With roots in the control and design category.

Without a WHOLE bunch of data, it would be useless to speculate what your problems are. We'd need to know how the boiler is being controlled (Vision 1 or none), zone valves? Non electric TRV's? pressure activated bypasses?

I seriously doubt that the use of a side arm for DHW is your problem, unless you are missing or have fouled check valves. To avoid short cycling, the DHW buffer tank can be used, but before we can even begin to help you out, you will need to deliver a whole bunch of information, including photographs, drawings, load calculations etc.

There are no easy fixes to complicated problems/systems. Done correctly, you will have the ultimate in energy efficiency and comfort. Done wrong, you will end up with a never ending nightmare, as you have seen. It can be done, but usually requires thinking outside the north american box of tricks to get 'er done...

ME

Jim Franklin

Radiant areas

Guys, the one fundamental thing you are all ignoring is that radiant heating is a function of surface area "y" at temperature "x". The key to getting warm floors in a super-insulated low heat loss home is to use smaller radiant floor surface areas at higher temperatures (78F to 82F) to get the warm floor in foot traffic zones without overheating the house. To get heat output "z", you can use large floor areas of radiant at low surface temps, or use smaller radiant floor areas at higher surface temperatures. The challenge is where are the best places to get the warm toes while not overheating the space.

Controls- high-mass radiant systems = constant flow/variable temperature.

Fast-acting solar gains- then the exterior shading and/or the windows are the problem. One CANNOT match a high mass radiant system with any kind of space that has fast-acting transient loads. Address the loads, and the load profiles first, then design the system appropriate for that space. A high mass radiant system is a poor match for a space with fast-acting thermal load variations. Use low mass radiant in those kinds of spaces, so the radiant system can react quicker to match the thermal load profiles. Why do you think the Euros are using small panel rads in their highly efficient homes?

Mike T., Swampeast MO

You really might want to look into FHVs (floor heat valves). They're similar to TRVs (thermostatic radiator valves) but have an extra adjustment to balance loops of even greatly different lengths. FHVs are limited to about 10,000 btu per valve, but it doesn't sound like that will be any problem in your case unless you have an extremely large room.

The good thing about FHVs is that only those spaces experiencing significant solar gain will have reduced flow--all the rest of the spaces will be unaffected. Regardless, the boiler will only see the load of the entire system--not a load made up of a number of different zones.

High solar gain--usually in mainly south-facing rooms with lots of glass--is always a problem. The passive approach is to use an extremely massive and well insulated floor as a sort of solar battery. Yes, the room air temp with fluctuate more than via active control, but in favorable weather, the heat is essentially free. If there's still too much passive solar gain, then simple blinds on the windows are amazingly effective. Great if such are both motorized and automatic, but such can be very expensive. When additional heat is needed, it's often best to use panels or baseboards instead of trying to heat the floor itself.

If passive solar wasn't really your intent--it just "happened"--then my best suggestion is to avoid radiant floors in spaces where it's most likely to be a problem. Use panels or baseboard--preferrably with TRVs--instead.

Gordy

Geoff

What about the use of the modcons, and the never ending effort to supply them with the coolest return temps, and having the supply temps on the edge of just off setting an envelopes losses. All in the interest of getting the most out of what a modcon has to offer....and a well designed system. I think technology has created another issue which has more to do with a consumers expectations of the warm floors.

What you say makes complete design sense, and I think that is what everyone is thinking they have to do. But as ME mentioned the consumer needs to be educated that the warm floors may be a thing of the past if you build a super foam dome which has always been the attraction of RFH for the consumer.

I have radiant ceilings and floors love them both but the ceiling is faster reacting,and is not limited to things blocking its output as floors. I even have rooms with both emmiters.

Gordy

Leo G_101

Panel rads

and ,....gulp!.....electric resistance floor heat. Seems to covr everything.

Leo G

Gordy

electric floor

If your kilowatt rates are cheap. Min are close to .11 cents not cheap! way more than NG.

Gordy

troy_8

Electric Radiant

In many cases low mass electric radiant is an alternative. It is room by room controllable and reacts fast. And with gas and oil increasing at a much faster rate in most areas the electric option needs to be explored. I know that offends many of your senses but think about it.

Mike T., Swampeast MO

For one I NEVER forget that any form of hydronic heating is a function of surface area "y" at temperature "x".

The original poster didn't say his customers were complaining about "cold" radiant floors, so I never considered that in my replies.

Gordy

rates

At 3.14 for 100000 btus of electric verses 1.14 for 100000 btus of NG after tax title and license. It would be smart to keep the heat source open to alternative fuel sources. Electric radiant does not allow that.

Gordy

Unknown

We DID,,,

have an interesting discussion on this very topic just a while ago. One problem I see is that the 29,000 BTUH is at design temp, which I assume is 0*. So when it's more than 0* ODT you need even less than the 29,000. Which is probably the case most of the time. Another I'm seeing is the lag between the loss of solar at the end of the day and the reaction of the floors to make it up. I wonder if a buffer tank and some kind of reset on the loop with constant circulation would alleviate any of this? Maybe an indoor reset? Where as indoor temp rises the water temp to the floor drops and when the solar starts to lose it at the end of the day the reset will begin to increase the water temp to the floor. This way the floor never totally cools off. Maybe, during the day, the water moving through the floor loop wants to be no more than desired room temp and as the sun sets it can then be brought up gradually to pick up the load from the solar. Just an idea to be tossed around, I have no practical application to point to for a case study. These new super insulated houses are running into a situation where at this point in time there is no equipment out there small enough to handle these tiny loads efficiently. A lot of us are looking at it though. I, for one, would be very interested in whatever followup you can provide on your situation.

Mark Eatherton

Free Deer Foam Slippers with each Radiant Window Purchase :-)

Geoff, I hear what you're saying, but in a real world, it is difficult at best to predict where the people WON'T walk, and when they are paying what they are paying for "warm floors", it tends to lead to a disgruntled customer.

If they have radiant ceilings, or other radiant surfaces, they don't care where the comfort comes from, so long as they are comfy, no?

As our friend in the industry, Robert Bean says, Design to the occupants, not the building.

ME

Uni R_2

Electric's already part of the heating equation...

A Grundfos 15-58 on low uses 60 watts which is over 200 BTUs or in a 24 SF bath about 8.5 BTU per SF worth of heating.

When are the cheap high efficiency pumps coming to market? Without them, electrical grid looks like the better value compared for small area applications.

Unknown

I always,,,

put it to them this way. I tell them the idea of warm floors is a misconception, that, in most cases if the floors feel warm the space will be too hot. The floors will not feel warm, they will just not feel cold. Ideally, the floor will feel neither warm nor cold. I stress the reason we want to heat this way is not because we want warm toes but because it is possibly the most efficient way there is to heat. I make this all very clear up front.

Having said all that, I was just over at the big house I did. I take my shoes off when I go inside now. I was never into booties. Anyhow, I went up to the third floor bathroom in my socks because one of the airhandlers is accessed from there. The first thing I noticed when I stepped on the bathroom floor was it felt just slightly warm. I believe it is set for 77*. Glee would best describe my feelings on that.

Not letting your floors cool off as much might be the key to eliminating the lag. The short cycling/DHW issue, I'm still thinking turbomax (not ergomax). I'm also thinking Grundfos variable speed pump regulated by either water or floor temp that pulls off and returns to a buffer tank (Turbomax) with some kind of mixdown for the temp, run it at like 100*, in your case I'd shoot for even lower if I could get it there, let the pump speed maintain the floor temp. Run it 24/7. I'm imagining that given your load, it will not be a very big pump and will run at very low capacity the majority of the time which means your electric load or draw should be very low, less than .5 amp I would think.

Tekmar has a radiant T'stat that monitors floor and room temp. It will shut the floors off if the room gets too warm. That might be useful as well.

What temp water are you running in the floor right now?

Jim Franklin

Still cool return with limited Radiant Areas

GKaske: you can still get the coolest water with the Mod-Con- all you need is limited floor areas at 78F-80F to get the warm toes, so you'll have your 75F heating water return temps anyway. It's about tuning the radiant surfaces to match the heat loads and to get most of the warm toes in there as well, IF that's what the homeowner wants.

Jim Franklin

So Noted.

My post wasn't directed to any one post, or yours specifically. As heating system designers, I think the next step for "Comfort Technicians" is to actively participate in the source and type of heat losses first, before applying a heating system, so that the heating system design is a best match for the type of heat losses, the occupant's comfort perceptions, and all the other good stuff on the way by - energy efficiency, human comfort, hands-off steady state control, etc.

Jim Franklin

Yah, but

At least you can get pretty close to predicting where they WILL be walking. Generally I think that the furniture arrangements and floor locations of where folks will want that warm toes feeling can be captured in the house design - bathroom floors, floors on either side of the beds, kitchen floor - where do you normally walk around in the morning to hit the coffee machine switch and settle to read the morning paper?

I'm talking from the point of view of more custom homes, since the super insulated homes aren't generally tract built pieces of crap, and they seem to be built by someone doing their "dream house", so the room use, layouts and lifestyle ought to be fairly well known.

Mark Eatherton

Reminds me of the time...

I was at an RPA conference, having lunch, talknig with the other participants. One of them, a lady representing an electric radiant floor company said "I NEVER put heat beneath the bed... It's a waste!"

To which I replied, "What if the consumer decides to move the bed to another wall, you know Fung Shui style..." She got this horrified look on her face... and never said another peep :-)

But I do hear what you are saying. I appreciate your years of wisdom. Now, if we can convince the other 99% of the industry, we MIGHT make some head way... It's not just about heated floors, its about human comfort, in what ever way works best. And floors, with all their foibles (high R values, different emmiting surfaces, differing masses) are the least forgiving.

ME

Mark Eatherton

Grundfos makes a VS pump???

UL aproved for use in the USofA?

I didn't know!

Still waiting...

ME

Mike T., Swampeast MO

Very nicely said, but you omitted one VERY important element of the system--the emitters.

The ultimate Euro design does use large radiant panels like floors, but when truly perfect their temperature does not change regardless of if the system is heating or cooling the room air. I don't believe they've quite achieved this yet, but they will--especially in their large commercial designs. In the meantime our Universities continue to produce so-called "engineers" who can't comprehend simple proportional devices like TRVs as anything but "Mickey Mouse".

Too bad that our trained engineers are so ridiculous to believe that they can somehow produce an environment equally comfortable to men in wool suits and women in short skirts/low-cut blouses in the exact same conditions!!!!

Unknown

Hmmm,,,

I thought they did? Or are they just still talking about it? I'll check into it. I DO know I approached them for a variable speed pump capable of ramping from 13 GPM to 130 GPM and they gave me a model number. Not sure on the small stuff now.

You know, the more I think about it, I remember Siggy talking about both Grundfos AND Taco making a small variable speed pump at this years REX. It sticks in my mind because I recall the Grundfos reduced amp draw as it ramped down and the Taco did not. I guess I got the impression they were already available. I'm going to look into it.

Unknown

VS pumps...

I have to admit I can't find a small Grundfos VS right now but here's Taco's version:

http://www.taco-hvac.com/en/products/Variable Speed Setpoint "00"^® Circulator/products.html?current_category=193

hot_rod

The Grundfos MixiMizer is a VS circ

it has been available for many years as a delta T circ. 15-42, 26-64, and 26-96 are all available in this style.

Personally I think all the pump manufacturers should skip the UL listing if it takes years and hundred's of thousands of dollars just for their blessing.

There are other listings that serve the same purpose that aren't quite as greedy and self serving as U..

hot rod

Mark Eatherton

Trust me, they don't have a residential circ with ECM technology

with U.L. approval here in the U.S. THey do make the Alpha in the European market, and over 10 years ago I was PROMISED that it would be in our market "next year". Am still waiting. They snooze, they lose. They initially used the excuse that there was a power compatability problem. THat didn't stop WILO from coming to the market.

Soon, the ECO from WILO will be on the market, and Grundfos STILL won't have their proven product here.

The only advantage to being the last one to market with a real cool tool is that it allows every one else to prime the market for your product... WILO has done a wonderful job at that.

Sad but true...

And for those who think that the 1542 and smaller circs are on the same level as an ECM motor, there really is no comparison in wire to water efficiency between the two technologies. Similar end results on the fluid side, but BIG difference in motor efficiency.

These DC ECM motors are like a TRACTOR. Even on their slowest speed you can NOT stop them with your hand. They will peel your skin right off before stopping. Amazing technology.

Some times, the truth hurts...

ME

GMcD

Education

I completely agree and it's been a soapbox of mine at our local University where I do a couple guest lectures - 30 years ago, "Building Systems" was a 3rd. year elective where I went to University, and here we are today looking at, yes, a 4th. year elective for HVAC Engineering in the Mech E courses. Elective being the key word- not a core course, just a filler for those who are interested. And even then it's a superficial course on "air conditioning" and just barely scratches the surface of human comfort, building physics, and passive building designs. If anyone wants to discuss THAT as a "Challenge to the Industry" in the other thread, knock yourselves out.

There is no way that the North American HVAC Design industry will get up to speed with the challenges of energy efficiency and human comfort engineering unless there is a wholesale change in the professional accreditation requirements and what gets taught in schools.

Unknown

Well that sucks...

What was Siggy showing us? I thought it was here.

The Taco should serve the purpose, just not as efficiently as I had hoped.

Unknown

regardless of the envelope, slab radiant is CHEAP. Cheaper than panel radiators, even if you have to add zoning, isn't it??

Slab system w/floor sensors vs panel radiators and I would expect the slab radiant to perform quite equivalently in almost any circumstance... no?

Unknown

LOL...

and butter your toast for you too...

Jim Erhardt_3

Good thread...

...and I have to agree that education - both of the installer and customer - is vital. Over the many years of conducting training seminars, I have always stated that if the floor feels warm to the touch that there's probably something wrong. To the masses, radiant floor heating = warm floors.

We have to accept - and educate - that maximum energy efficiency does not provide the highest creature comfort. In a super insultated home, the highest comfort may be achieved by "over radiating" the floors and off setting the heat gain (for the sake of warm feet) with mechanical ventilation of outside air. Having the ability to set the system for either "economy" or "comfort" mode might be a set-up to explore.