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The Wall
Mark Eatherton

Mark Eatherton

Joined on November 10, 2007

Last Post on July 22, 2014

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Paint that puppie HR...

@ July 22, 2014 9:48 AM in Electric Baseboard Vs Hydronic Electric Baseboards

I had a copper sheet radiant heater on the ceiling of my office many years ago. As I sat below it, with my system running full out, I really didn't "feel" that much heat pouring off of the panels.

I attached a delta T temperature recorder and confirmed my beliefs. Not more than a 2 degree delta T across the 4' X 4' panel,

I then painted the outward facing surface of the radiator with a flat white latex paint, and my DT jumped to 5 degrees F., and when I sat below the radiator, it felt like sunshine falling on my face.

Copper, especially shiny copper, makes a terrible heat emitter, and any radiator that is painted a metallic color significantly reduces the radiant output of the heat emitting surfaces.

I always wondered why the old upright radiators were painted silver, copper or gold…

Dan has an article in the archives written by one of the hydronic ancients that spells it all out. Check it out. As Dan say's, it pays to wander off the Wall. Lots and lots of resources in the Library.

Just joshing you about painting yours HR. I suspect you really don't need the extra BTUH output of it anyway :-) That is a beautiful work of pipe art from Pipe Dream Acres.

Thanks for all you and your family have done and continue to do for our industry.


A watt is a watt, just like...

@ July 21, 2014 8:35 AM in Electric Baseboard Vs Hydronic Electric Baseboards

A BTU is a BTU. There are only 3.413 btu's per watt, oil or not. The addition of oil to the convective process doesn't enhance the delivery of thermal energy. It only spreads it out over a wider time frame.

If you really want to deliver excellent RADIANT comfort, look into Cove Heaters They mount at the junction of the wall and ceiling and they WILL influence the Mean Radiant Temperature, and that drives the bus of human comfort.


Reverse calculation for head...

@ July 15, 2014 10:57 AM in How Long

1. Pressure test to confirm vessel integrity.

2. Connect a steep curved pump to the pipe with pressure gauges before and after the pump.

3. Read pressure differential across pump with pump running wide open and free.

4. Take manufacturers performance curve and figure out how many guppies per minute (GPM) you are currently moving.

5. Take pressure drop chart for the pipe you are connected to, and knowing (from initial differential test) how many GPM you are moving, and knowing the pressure drop of the pipe per foot per GPM, divide known overall circuit pressure drop by the pressure drop per foot (or one hundred feet what ever your chart reads) and calculate length.

The problem with air purging is that unless you have a substantial CFM availability (thinking tow behind compressor here), chances of getting a good and complete purge into buckets or drums is slim. And once you start flowing water out, you can not stop until it stops itself. Could get a little (lot) messy if you are not prepared.

Don't forget to compensate for fluid temperature in your calculations.

My assumption is that there are no obstructions or kinks in the pipe. Otherwise, all bets are off.


I definitely wouldn't have missed that...

@ July 12, 2014 8:17 AM in Radiant Ray is mia

Thanks for the picture HR.

I can now ask people if they've seen him.

If you know his whereabouts, call me at 720-375-3107


I hear you Gordy...

@ July 10, 2014 12:18 AM in Jury Rules That CSST is a Defective Product

And I hate to use the old saw of you can't fix stupid. We can only do so much in our efforts to protect people from potential life threatening systems. Can't tell you how many combustion air vents I've come across that were completely blocked off…

I believe that this lightning technology could be incorporated with a pressure sensor, and if the gas pressure drops after the strike has been indicated, then the system locks out. If pressure is stable, then it could automatically reset itself.

And you are right. Given enough nuisance calls, people will defeat ANY system of protection…


Solution to the problem...

@ July 9, 2014 8:09 PM in Jury Rules That CSST is a Defective Product

I have a solution to this problem. As stated WAY up in this thread, there is a LOT of this stuff in homes throughout the world, and it is just not real to think we can deconstruct peoples homes to repipe in rigid pipe. I know for a fact that the people who make this stuff also frequent this site and read these threads, so I HOPE that they view my recommendation as an inexpensive solution to a potentially ex$pen$ive problem.

There exists on the market, a device known as a "Near strike lightning detector". It is adjustable and can be set to detect strikes within 1 mile of its location. They are used on golf courses to warn golfers of pending lightning dangers.

There also exists normally closed solenoids rated for use with gaseous fuels. They are used in conjunction with LP detectors here in certain parts of Colorado, and shut down the fuel distribution systems outside of the building served if LP is detected.

If these two units are combined (lightning detector and solenoid) and a near strike is detected, the fuel valve is closed when a near strike is detected, annunciating a BEEP BEEP audible signal inside the affected dwelling, requiring the consumer to call their plumber to retest the vessel integrity of the CSST system, and if clear, reset the system to allow fuel to flow again.

Seems a lot cheaper to me than possibly having your product banned by the NFPA and being forced to recall ALL of your material from the field.

i have documented the date of the idea of conception of this product, but I never pursued it any further.

Remember me and my family in your will…


Best resource on the interweb...

@ July 9, 2014 9:16 AM in Radiant cooling

Is Robert Beans web site,

Typically, radiant cooling is set to handle the sensible loads only, and depending upon the actual loads, possibly not ALL of the sensible loads, but in most normal cases, can handle all of it. A typical installation requires tubing at 6" O.C.,and an approach fluid temperature of 55 to 70 degrees F.

If the tubing is at a wider center (typical) then it will carry half as much as it would at 6" centers, but in your case it would still help offset the loads.

The possibility of creating condensation using fluid temperatures greater than 55 degrees F are slim to none.

Chris, the airport in Bangkok uses a DOAS (Direct Outside Air System) to control the HUGE transient latent loads and environmental humidity that they see in that environment. They use large surface area finned heat exchangers, along with super cold water to wring the humidity out of the air coming into the building.

Radiant cooling is just like radiant cooling in that it affects the Mean Radiant Temperature. On the heating side, we use the "standing outside on a cool day in the sunshine" to give people an idea of how it affects us. On the cooling side, it is like "standing in a basement on a hot summer day". It "feels" cooler.

Having ceiling fans with a floor is a good idea to break up the stratified air to avoid a muggy feeling.

Radiant cooling is no longer a "theory", but instead is a p proven method of delivering excellent human comfort. Shedding as much load as possible in the first place using off shelf technology (reflective window coverings, operable screens to keep fenestration gains out, over hangs, etc) makes excellent sense, but radiant cooling is a possible option.

Robert helped Uponor in the development of the programs they use for calculating its ability to cool.

If you've never been to, plan on spending some time there to educate yourself. Robert does a fantastic job.

If you join the RPA, we can teach you all of these things :-)


Interesting stuff Chris...

@ July 8, 2014 10:45 AM in Peer review please...

We could learn a LOT from the ancients, if we'd just listen :-)

Oh wait, you and I are considered ancients, are we not :-)

Borderline Dead Men, standing in line waiting for the next threshold…


All great points HR...

@ July 8, 2014 10:37 AM in Peer review please...

And just so it is clear, I am not advocating flat concrete panels in lieu of properly placed solar collectors. I guess what I am saying, is if you are going to install a snowmelt system, why not take advantage of whats there energy wise for not a lot of extra cost and effort. It just seems to make sense to me. And yes, availability and load have to be matched, or storage taken into consideration, which will add costs. I see your points and they are well taken. It won't be for everyone, but commercially speaking, I do believe there may be some opportunities there that can and should be utilized.

In order to test all of this, its going to require some dependable instrumentation. Do you know of any flow sensors that are reasonable in cost and can be compensated for use with fluids other than straight water? I believe you were working with some Grundfos flow meters at one point in time.

I have the necessary computer power for data logging to show us the potential, and it is flexible enough to handle pretty much anyones sensors. I can get 32 points of monitoring, and 8 points of output control for fairly cheap. Just need the ultrasonic flow sensors to make it work.

Thanks for your perspective.

By the way, I seem to remember a European plan (Swedes or Danes) who were planning on doing this very thing (road based snowmelt/energy harvesting system). Wonder what ever happened with that?



@ July 7, 2014 9:59 PM in Peer review please...

What about degrading PV efficiencies over time?

I hear what you are saying regarding a 300% efficient device versus a 95% device, but still, using a solar PV array at a 20% peak efficiency versus a flat plate at around 60%?

My gut tells me we end up at the same place efficiency wise (except for your graphic delta T in storage example), but the ST systems efficiency will not degrade significantly over the life of the collectors, Having to completely replace the PV array before it has paid for itself just doesn't sit right with me for some reason. Plus, we can completely recycle a ST collector, but can't do the same with a PV array can we?

Lots of numbers to chew on. :-)

Buyer beware…

Thanks again for chiming in.


Thanks HR...

@ July 7, 2014 1:34 PM in Peer review please...

Much appreciated as always.

Obviously, this is still in its conceptual stages, and I don't want to limit the application to residential settings. Anywhere that there is a good and continuous hot water load is a good candidate. Restaurants are a great example. They can use the snowmelt system in the winter to avoid slip fall hazards, as well as decrease the maintenance costs (salt and chemicals are BAD for carpet and tile), and they can use the hot water it provides when available. Remember also that the operation of this system is not limited to the availability of solar energy falling upon the surface, although the advantages of that are quite obvious. There are times, at night, when the slab is still being exposed to significant energy potentials from the higher ambient air temperatures,

In addition to DHW, there are a LOT of other thermal loads that can be satisfied with low temp (120 F) energy. Hot tubs, swimming pools, spas, even some space heating needs. As for storage, there are a whole bunch of new phase change materials coming across the pond that will revolutionize thermal energy storage. That, and good old Mother Earth ( Plus, as we have proven over the years, a slab, at night makes an excellent heat emitter, providing a passive cooling source for radiant cooling loads.

I think it is a huge opportunity staring hydronic contractors in the face. Once we prove it is technically and economically viable, we (The RPA through IAPMO) can start pushing for tax credits for the equipment necessary (except for the slab and boilers) to make it work. How many square feet of snowmelt systems is currently sitting there doing nothing for most of the time, right next the the physical plant for heating hot water and buildings?

I think just about every system I installed would make a great candidate. Plus, by cooling the slab, and keeping it relatively stable temperature wise, we lessen the opportunity for thermal expansion and stress related cracking of the slab. Imagine the looks on peoples faces when they step onto a pool deck that is cooled? Probably as nice as the look they have on their face when they step on a warm floor for the first time...

Need to round up some volunteers (equipment manufacturers and end users as well) to document the potential to move the initiative forward. I have one candidate (consumer) already, and am looking for more.

Did I mention that we can "make" water by keeping the slab below dew point, and can use that water to maintain our Xeriscape Landscaping? Green, green, green, green, green. Plus, by condensing moisture out of the atmosphere, we can slow down global warming, because in reality, its not the Co2 that's causing issues, it is WATER vapor :-)

The Bean is giving me many articles from IGSHPA folks to read. They've been looking at this for some time now. I know of a building in Aspen Colorado that has received numerous awards for its design that uses its snowmelt system as a cooling tower.

Thanks for chiming in Bob. I look forward to your contributions.



@ July 3, 2014 2:53 PM in Peer review please...

Here are some conceptual drawings I generated. My apologies for the roughness of some of them. I've been away from Visio for way too long.
I am posting four concepts.:
1. basic high efficiency SIM,
2. High Efficiency SIM that also does DHW (for the family with lots of teens),
3. SIM with single stage DHW preheat, and
4., SIM with 2 stage DHW preheat.
Comments and questions are welcome.


Our deepest condolences...

@ June 29, 2014 11:06 PM in One of the greatest heating tech' has passed away

To the Milne and Aiello family. JCA was one bright candle out in the deep dark woods of life. He will be greatly missed, and passed way too young.


Follow us on Twitter...

@ June 18, 2014 11:07 AM in Follow us on Twitter...

Wallsters, I have recently begun Tweeting on Twitter. For the longest time, I was worried that too much tweeting could cause Chirpies. I am told by authoritative people on the subject that Chirpies is a Canerial disease... From what I understand, it's a real Birden to those who have contracted it, but they are stilling winging it... (I'll be here all week, and don't forget to tip the wait staff :-))

These will not be personal Tweets, but rather Tweets about what's going on in the RPA. Please, follow me.
[u][color=#178bb5]@[/color][color=#178bb5]Radiant_Panel[/color][/u]  is our Twitter handle. If you have a Twitter account, by all means, please share it with me. I am interested in knowing what's going on in our industry.
 And thank you for joining us in this very worthwhile hydronic organization. If you've not joined or rejoined us, why not? What are you waiting for? Go to and click on the JOIN button. Less than a buck a day to belong. Won't even make a dent in your beer money :-)
Thanks for indulging me :-)


Code reminder...

@ June 12, 2014 2:29 PM in Code reminder...

If you have an interest in influencing the outcome of the Uniform Solar Energy Hydronics Code, time is running out. Comments must be made no later than 20th of June, 5:00 PM PST.

You can go to and click on Codes, then click on USEHC and all forms etc. are available to allow you to make comment on the proposed code.

If you have any questions, please feel free to contact me at

Thank you for your consideration and involvement.


Don't miss this opportunity

@ June 4, 2014 12:05 PM in An offer you can't refuse...

Time flies when you're having fun. Join us won't you.

Thank you for your consideration!

And thanks to the Holohans for getting behind our efforts.


Thanks HR...

@ May 25, 2014 10:38 AM in Peer review please...

Appreciate your input.

Matching load to availability or coming up with cost effective thermal storage will be key to the efficient operation, but all technically feasible in my opinion. I ran my idea by Robert Bean who gave me a bunch of leads to research work done by IGSHPA. We will have to develop the software necessary to model it, but that is the easy part:-)

Thanks for contributing.


All the above...

@ May 22, 2014 4:34 PM in Peer review please...

I don't like the use of antifreeze unless absolutely necessary. I envision reverse indirects for stage 1, and WSHP tied to the potable side of the tanks for stage 2, and or the secondary side of heat exchangers going to other loads. As with any hydronic question, there is only one correct answer, and you already know what that answer is, so I won't say it again :-)

Thanks for chiming in Frank. I always value your thoughts.



@ May 22, 2014 1:12 PM in Peer review please...

Yes Frank, antifreeze is still required. No way around that.


Hi Sal...

@ May 22, 2014 1:08 PM in Peer review please...

What I DON'T want this discussion to do is to go to a discussion on APGW.

I think my opinion is fairly clear, and that is, regardless of wether you believe in it (APGW) or simply believe it is a natural change that we have to ride out, conserving our EVERY resource is important. Waste not, want not is my M.O. I do agree that man has done some long term damage to this planet, but I suspect Mother Nature has some things up her sleeve that we have yet to see. She is a resilient woman who has been around for billions of years, and will continue to be here for billions more. Regardless of what man does on her surface.

The reference to Carbon Foot print is to show the environmentalist who are dead set against the use of SIM systems that it has potential, even in THEIR arena, using THIER chosen verbiage.

Sorry to cut the conversation short on this thread, and if you want to start one, I'd be glad (as I am sure millions of others would as well) to chime in.



@ May 22, 2014 8:16 AM in Peer review please...

Rich, check out They make what you want. Can be used as a roof or a radiant ceiling/wall assembly.


Peer review please...

@ May 22, 2014 6:58 AM in Peer review please...

Wallies, I have been working on this idea for nigh on 20 some years, and I want to get some feed back from my fellow Wallies to make sure I am not too far off in the weeds.

Here goes. Snowmelt is viewed by environmentalists as a terrible waste of natural resources. They don't care that there is an associated reduction in slip fall hazard law suits, or reduction in the use of snow melting chemicals, to say nothing of the documented floor maintenance cost reductions. They don't like it.

What if the SIM slab became a solar powered low temperature collector/heat emitter (think heat rejection into the night sky).

It would maintain the slab at a minimum of 35 to 40 degrees F. My thinking is that the slab will generate more energy than it consumes. It will benefit not only from the solar thermal gain component, but also the ambient air energy potential, which is huge.

It will obviously need to be matched to a load. If that isn't possible, then the production of the slab is stored in either VBH thermal batteries, or sub surface Thermal Storage batteries.

My goal would be to eventually gain tax credits for proven use to availability ratios (Continuous COP) of 3 to 1. Using WSHP makes that a snap.

I'm thinking it could be 2 stage. Stage 1 is a direct exchange to any load that needs it and can use it at a given temp (I've seen 140 deg. F stagnated temperatures on slabs in middle of summer), including but not limited to DHW pre-heat, swimming pools, spa's and hot tubs, and even some space heating loads. When it is too cool to use for any of these loads, then the WSHP kicks on, drawing the slab temp lower (thereby increasing its "in flow" delta T) and takes it to one of two operating temperatures, depending upon the mode of operation. If it is in "water production mode", then its surface will be drawn down low enough to condense, but never less than 35 degrees F where frost might form.

If the slab does get called upon as a snowmelt surface, then all energy draws off of the slab stop.

If it is operated in the "No Water Production" mode, then the slab is never drawn to within more than 5 degrees above the dew point. But again, never less than 35 to 40 degrees F, unless doing so naturally. Dew point could be monitored and calculated know the rH and ambient temperatures. This would control the fluid temperatures being run through the slab.

The GREEN advantages of the system should be fairly obvious.

1. Using energy that is free for the taking (solar and ambient temperature differential), thereby,

2. Reducing the heat island effect and hence forth reducing the effects of alleged global warming.

3. Reductions of thermal stress typically associated with significant structural degradation of concrete slabs. Swimming pool decks would actually feel cool to the human touch (thinking bare footed children running around a swimming pool)

4. Controlled production of water (humidity) further reducing the potential of "green house" effects associated with alleged global warming. (this is not a conversation on wether or not its real or perceived. Climate change is for real)

5. Significant reductions in carbon foot printing of all connected loads.

6. The previously touted benefits of snow melting systems.

7. Can act as a heat rejection system (active or passive) at night for the production and storage of chilled water to handle peak loading conditions for buildings using radiant cooling. Night sky re-radiation through the use of proper colored concrete dyes has been shown to enhance absorption and rejection of thermal energy.

Feel free to chime in on any benefits I might have missed.

All of the components necessary to make these systems work are already available off shelf. I am going to generate a drawing in the next few days depicting how all of these components fit together to make this thing work.

I welcome your thoughts, positive or negative.

By the way, this is not a new concept, and if you or someone you know has deployed this technology before, please contact me. We need all the powder we can get for the legislative bullet to get credit for the cost of the components necessary to make this idea work. I think I remember something about Mario Andretti heating his olympic size swimming pool for free using his SIM driveway. I'm sure there are more of them out there…

Thanks for taking the time to read this lengthy submission, and thanks in advance for your comments.

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