radiantec

radmix

I'm a heating contractor that is used to using Extruded aluminum plates for my radiant install. I have a customer that said my quote was to high and that Radiantec told him that there system will work @ the same supply water temp @ design then the extruded plates even with one tubing run per bay 7/8  tube. I find this hard to believe. I also think with a thermal imaging camera you would also see striping in the floor surface. Do any of you have any experience pro or con with working with this system.

heatboy

Request the owner....

.....show you Radiantec's heat loss and design for his home.  When he tells you they didn't do one, show him yours.  Case closed.  If he still balks, give him your card, tell him to call you for service (because there will be lots of it) and walk away.

Mark Eatherton

Suggestions...

First off, your gut instincts are correct. Your other gut instinct should tell you that the owner of Radiantec is extremely litigious, and will drop a cease and desist order or threaten you with a defamation lawsuit in a heart beat. Be careful what you say.



Tell your consumer, that by code (IECC) a complete heat loss/heat gain calculation must be done, and ask them if they ever received one from their internet supplier.



The code (IAPMO, UPC) also requires that if a water heater is to be used as the heat source, that it be sized such as to be able to handle simultaneous loads at design conditions.



I have personally had numerous dissatisfied customers of internet peddlers ask me to come to their aid, and they were so dissatisfied with the experience that they refused to report their experience to the BBB or like associations. they said they were told by the provider that they had not installed it correctly, hence it would not perform. Hog wash.



Baffle them with your brilliance, and if they can not see the light, walk away. They have done a little study and became EXPERTS over night. You don't need the headaches.



Best of luck. Sometimes, ya just gotta walk away...



ME

Dave Yates (GrandPAH)

bacterial amplification

ME,



You'll be glad to hear my certification class for the Daikin Altherma delved into the need to incorporate a "sanitation" mode for their DHW tank (no other aux use either) to raise the temp to 156F each day. The instructor didn't beat around the bush either - the L-word was out and freely discussed from the start. I just sat back and smiled. A few solar companies are incorporating a sanitation mode too.



radmix: If that's an open system (mixing the radiant hydronic water with the potable water) - do yourself a huge favor (and your customers' too) by researching bacterial amplification issues with potable warm water. I've never yet discovered any credible evidence that supports using an open system. If the owners insist it's OK to install that system as an open system, I'd run - not walk - away. But, do your own research and form your own opinion. The best customers are well-informed customers because once educated, they will almost always make the right decisions.

scott markle_2

water heater

Mark,



Most tank hot water heaters can't supply a continuous DHW demand in the first place. We don't size boilers by adding DHW and heating loads why should we do this with water heaters.



OK- a water heater used in a combi system will not have a DHW priority mode, (unless we put a flow sensor on the domestic line) and for this reason we do have to be careful with sizing, but adding design load and continuous DHW seems a bit restrictive to me.



I rather like HX isolated combi systems and wonder if the code you mention is a bit overly restrictive.

Mark Eatherton

I guess it depends upon your perspective Scott...

As a contractor who doesn't deal with tank type gas fired water heaters, it sounds perfectly restrictive to me :-)



If I were in the habit of using tank type water haters for doing space heating and DHW, I would agree that it is probably over restrictive. This is how the code authorities give "disincentives" for people to do things that really don't make sense in the first place.



By not having a means of DHW prioritization, the appliance COULD be subjected to loads exceeding its capacity, which COULD put it into a continuous condensing situation, which we all know WILL cause the appliance to have a shorter than usual life expectancy.



BTW, the code does NOT require the compounding of the loads when using a boiler as the heat source. This is due to the AHJ knowing that we prioritize our loads and don't overload our systems.



I don't make 'em (The codes), I just reads and interprets them :-)



ME

scott markle_2

perspective

Mark, I'm kind of proud to have implemented this before it got so much attention by siggy.



To be clear I don't have much interest in non-condensing gas appliances, I'm using the HTP Pheonix, take a look my pictures.



The code restriction you mention is not really a problem in my application of choice. I like constant circulation on slabs, but I'm fairly convinced that when you target sub 90 deg. temperatures most boilers will short cycle on sub 20k loads. I'd give the tank condensing appliance a second look for these kind of applications.



With well insulated structures DHW starts to become a significant fraction of energy use, yet most mod cons are sub condensing when maintaining 125 degree tank temperatures via an indirect . Eliminating the HX and submerging the combustion chamber gives 95% for heat and hot water.

Constantin

Interesting, isn't it?

I had the same epiphany reviewing the BBB records for builders in this part of the world some years ago. Plenty of companies on file, none with egg on their face. How does that work? I suppose HO reluctance to share dirty laundry is part of the equation, as is some guys going out of business and reinventing themselves as the same kind of business the next year. But bottom line is for all the dissatisfaction with the builders, the BBB doesn't show it.



As for water heaters being used to heat domestic needs, I agree that the boiler and the domestic water shouldn't be mixed. At the very least, a flat-plate HX is so cheap that the lower cost components you can use on the heat side likely justify it alone (i.e. cast iron vs. stainless circulator bodies, etc.). Furthermore, there aren't that many water heaters that are also listed as domestic heating appliances, and those that are, tend to be pretty expensive. In no case would I attempt something as silly as attaching a low-temp heating system to a standard gas water heater, BTW. They're not engineered for such use and such use can corrode the heater in no time causing leaks, CO, mayhem, etc... we've seen the pictures.



Anyway, as usual, Mark, spot-on advice. However, I wouldn't single Radiantec out on principle, I have seen similar results from supply-house-supplied diagrams, etc. that were followed to the letter. Thus, the execution was great, but executing a bad plan beautifully doesn't necessarily lead to happiness, now does it? It's why folk like NRT Rob are so useful, IMO, thinking through a problem and presenting the homeowner with a plan that any contractor can follow and be sure it will work.

Gordan

Constantin...

Could you please explain? After all, a standard gas water heater operates in low temp mode all the time - most of them have aquastats that can't even be set above 140 F, often less. Entering domestic water can be under 40 F in certain areas in wintertime. So, temps alone should not intuitively be a problem - is it the low temps combined with more-or-less constant demand during design conditions?

Mark Eatherton

Not singling any one company out...

Hence, my use of the term internet peddlers, which covers a lot without pointing at any one particular entity.



ME

Mark Eatherton

You have a lot to smile about...

were it not for your efforts, the disease would not be significantly recognized by our industries.



Good job Dave. Keep up the good fight. I'm right here behind you.



ME

NRT_Rob

your client is confused

radiantec says that plates don't do much. check out their website and read up to see what you are up against.



I suspect they are saying this for a couple of reasons:



1. they are using very poor plates. So I suspect they are right when they say they don't help much. Tubing contact is nearly non existent with their plates and subfloor contact is poor too. As we know, contact and conduction is king which is part of the reason the heavy plates are so much better... very tight and continuous tubing contact. Plus, they are lightweight plates, not extruded heavy plates.



In reality, heavy plates will blow their staple up out of the water. I would expect a minimum of a 20 degree water temperature improvement on a high-average 20 bTUs/sq ft load under wood. Probably more like 30. Never mind the increase in available output if that's an issue, and the reduction of noise possibilities and much more even heating.



2. They are not doing BTU testing, they are simply using infrared cameras, and it's nearly impossible to do energy testing with just temperature. It is like trying to measure your speed with a yardstick.... you might get the distance, but it's missing a key element there. We've seen far more rigorous testers mess up on output testing (cough *rehau* cough) and it's hard to do properly. I think, frankly, that they don't know what they are doing or how to properly test these assemblies.



What I find really funny is that they say on that page that the difference between 1/2" and 5/8" was nearly negligible, yet elsewhere in the site they claim that huge pipe emits significantly more BTUs per foot. Very funny indeed.

Constantin

Very different duty cycle

Many moons ago, I was part of a team looking into ice cream parlor operations. One owner described how his heaters failed like clockwork every year on account of high demand - they would rust out. This abuse was on account of the very little flow of warm water you can see in any ice cream shop to clean and warm the scoops after use.



Similarly, some manufacturers of standard gas water heaters mention in their i&o manuals that observing condensation on the tank (through the intake mesh on the side) is perfectly normal during initial fill & operation. Point is, the duty cycle of a standard gas water heater is designed around intermittent demand that may not even fully deplete the reservoir.



The heating needs of most homes are much more constant during the winter, much like the hot water demand of that ice cream parlor. We've seen pictures here of standard gas water heaters being used as heat sources and the area around the draft hood and below was littered with rust balls. Seems like a good means of destroying the water heater and potentially causing dangerous combustion.