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Joined on August 27, 2007

Last Post on July 30, 2014

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@ July 9, 2014 7:57 PM in Getting into mod/con business

I'm not a huge fan of a common water heater as a heat source. The small boiler would be my choice.

We had this discussion many years ago at the RPA. Larry Drake the director always wondered why an "H" stamp is such a important feature. Why does a low temperature heat source need to be called a boiler even. Boilers is an old term dating back to steam days :)

If the "heating appliance" can be built safely with all the appropriate LWC, over temperature, no flow, low pressure cut out, gas train safety, etc, why not. Most of these controls are standard on Euro origin mod cons, or the connection is provided for LWC switches for example. Most of the mod cons that came from off shore did not have the H stamp early on and proved to be equally as safe, or safer than H stamped products. The Euro boilers meet some fairly strict standards.

Some of the tank style "boilers" on the market do not have the H stamp, and have adequate protection, like their mod con kin. Maybe it's an entire mod con assembly shoved into a tank? I think my tank style condensor has a vacuum cleaner motor for the inducer fan. Sure is robust.


@ July 9, 2014 7:39 PM in Hydronic underfloor used to effectively enlarge direct solar thermal mass?

We did a passive home in Utah many years ago that had black, stamped concrete in the south facing great room. We did what you are considering. t didn't end up moving much energy around as we had expected. We watched it for a few heating season with some simple hour meters.

The cost for the additional controls to allow that, may not have been recovered with any energy savings.

I think you would be better off using the $$ amount on the building shell upgrades, best insulation, triple glazed windows, top quality heat pump brand, etc.

With a super insulated, passive home the energy costs should be very low to begin with. You may see heat load numbers in the single digits for BTU/ sq. ft. The back rooms not seeing that passive gain directly, can still be warmed with some air movement from the ERV or other exchange device, with some planning.

The biggest complaint was overheating. Wakeing up in the morning after a cold night had the slab with a belly full of energy. All that mass needs time to ramp down, it is not a quick responding system, a concrete slab.

If I were to do it again i would look into low mass heat emitters, maybe some radiant floors in the bathrooms and tiled kitchen floor.

Most of those early passive homes in the sunbelt mountain areas had their windows and doors open on sunny days, too much of a good thing can be un-comfortable when it comes to a 90° passive home.

This article may help put some numbers to the question. Thanks to PM Magazine for archiving all this info.

I do see the point that bc is making

@ July 9, 2014 6:54 PM in Getting into mod/con business

keep in mind a modern cast iron or copper tube boiler is much different from a 30 year old one, size and mass, ignition system, insulation, to name a few. A 100K cast iron is not that much larger than a mod con these days.

What is the most expensive component to replace on a cast iron boiler? What the most common failure on a mod con? Price a inducer fan and motor, available only with the circuit board attached. A mother board $$?. These are the unknown, or known unknowns that can throw the numbers out of budget quickly.

Not to go back too far, but standing pilot boilers ran troubleefree for decades, some without any maintenance over that life cycle.

I know some contractors only install mid efficiency equipment in the very rural areas where parts availability is slim, and a service call round trip could ring up hundreds in fuel and windshield time, usually requiring two trips. Parts and multiple service calls could ring up a grand rather quickly.

Keep in mind the elements out of our control, low gas pressure, ever changing fuel BTU content, obselete OEM parts, all realities. These are some of the common realities of 90% equipment. Ignore PVC venting for this discussion :)

At the end it is what is best for the individual customer, and their expectations for on-going yearly maintenance.

Many of us here embrace modcons, but we are able to service and repair our own stuff, the consumer doesn't always have that option.

would that condensate

@ July 9, 2014 11:08 AM in Radiant cooling

water be the same a desalinated water. Able to be treated for drinking?

SRCC is rating

@ July 8, 2014 10:25 PM in Low flow air solar walls

and certifying performance of air (transpired) collectors now. Some some actual performance and durability data is available. Looks like your brand is one of the listed.

contact them in NJ

@ July 8, 2014 10:13 PM in Old Vaillant boiler info needed

Looks like they still maintain an office there.

been around for some time

@ July 8, 2014 3:12 PM in Ecodrain gets US building code approval

the GFX brand started in 1986, must be plenty, thousands?, of them installed.

Larry has one in his place, what maybe 10 years now? Something to be said for no moving parts or electronics.

Again, like anything, in the right application that would be an excellent ROI, considering maybe 800 bucks installed.

Wonder what that 25 lbs of scrap copper will be worth in 20 years or so :) should it wear out.

understood and agreed

@ July 8, 2014 11:12 AM in Peer review please...

the concept of storing energy in the ground. Really a GEO system IS solar energy. Cave dwellers in Colorado lived in a hole in the rock facing south. I doubt they had much snowmelt square footage, however.

My question is how a surface slab could store or exchange energy better than well or trenches into the constant 55°f earth temperature.

The insulated slab will hover around ambient except for sunny summer months. The bore holes or deep trenches always have around 55°F to offer.

The surface slab sounds more like a large air to water exchanger that you can park on :)

Sure there is some DHW pre-heat potential, not nearly what a manufactured collector could produce, however.

We all know and acknowledge that energy storage is the holy grail. The whole world is looking for the best most efficient option, especially Europeans where todays fossil fuel price is $8.56 per gallon.

So far this year I have read about energy storage in compressed air, latent HX materials, flywheel inertia, all sorts of batteries, it's all being considered.

Best I can tell a modern HP with the latest refrigerants and high efficient ECM motor technology, tied into a earth loop or pond loop is as good as it gets. If you want heat, cooling and DHW at the flip of a switch, as most do, not under the suns fickle terms.

I think we all agree on the HP as the key, the discussion seems to be slab on grade, or reach deeper into the ground for the energy exchange.

I'm onboard for trying ME's concept, I just wonder how a residential pilot project, ME spoke of, without a huge summer DHW or heat load will pencil out? Nobody will spend $50,000 or more to save $300.00 per year?

Currently they are capping off NG wells with a glut and low prices. If you have the $$ to install snowmelt, pay the NG costs so the oil guys can make a decent living and the radiant contractors have work. Isn't it mostly the oil folks building those custom homes with large snowmelts in the mountains, currently? Or their financial guys.

With the US becoming the largest oil producer, better melt snow before the world comes shopping for that NG, prices may go up.

Certainly the bright folks at NREL would have some knowledge in these areas, I'd like to hear their thoughts. All this is calculate-able, the data exists at places like IGSHP and NREL and many other Energy Universities across the world.

an unglazed collector, aka a radiant outdoor slab

@ July 7, 2014 11:38 PM in Peer review please...

lying horizontal, what is the efficiency of that? Look at the performance slope on an unglazed collector, which a driveway or parking lot slab could be considered. Although an unglazed collector would have the absorber directly in the sun. The slab would have the absorber tubes 2-4" below the direct sun. So probably less efficient.

An unglazed collector has great performance compared to flate plate or evac tubes when the ambient and fluid temperature are close. Once the ambient drops 10- 20 below the fluid the unglazed goes in the toilet, performance wise. Not to mention wind across the slab or vehicles parked over it in a commercial parking lot.

So first consider the cost of tube and insulation, labor etc to install lets say 10,000 square feet of slab. How much would you bid to tube and insulate 10,000 sq ft of slab the was to be poured? Concrete and labor to install is already covered, just the cost to turn it radiant. Divide that by the efficiency of that slab collector across 12 months.

I'm thinking that dollar amount spent towards flat plate or evac tubes would give you much more energy, and perform in the cold months to 120- 140F, whereas the slab would not exchange much energy below 80°F ambient.

Here is a performance graph, notice how an unglazed collector drops as temperature drops. Once the ambient is about 20° cooler than the fluid, you performance is completely gone. unglazed collectors, or slabs are good for providing 80- 85 pool water temperatures in warm climates.

That slab would make a great heat dump, but you have no solar thermal to dump :)

Someone good with solar simulation could model 10,000 square feet of un-glazed collector with 10,000 gallon of storage and see what the SF is. Then model that same load with flat plate or tubes and compare the required square footage and see how the costs work out.

True the PV is less efficient compared to thermal collectors, but there is ALWAYS work for the pv, unless you have a consistent all day DHW load all year you thermal numbers will never pencil.

Some thoughts for that load year around water parks, huge daily DHW and indoor pool loads. Prisons, plenty of them around, most over crowded. Predictable daily DHW loads.

NRT Rob has some pretty good, actual data comparing PV to thermal on one of the solar threads, but not unglazed thermal.

nice, a horizontal style

@ July 7, 2014 9:28 PM in Ecodrain gets US building code approval

good move. May be the best bang for your fuel saving dollars, these drain HXers.

should be fine

@ July 7, 2014 9:16 PM in Fill, vent air, purge, 3/8" PEX, 25ft elevation change

is it a radiant loop? There may not be a good method to add a high point vent.
You would want a good air vent and hydroscopic cap for extra protection, if it is a panel radiator, for example..

What is the total elevation from equipment room, expansion tank location, to thr highest point in that upper loop?

Adjust the system fill pressure to assure the highest point in the piping has 5 psi. That will help assure air free operation.

For example, 3 stories, maybe 27' from mech room to upper level 27 X.433= 11.6 , add 5 psi for a 16.6psi. call it 17 psi fill pressure.

The expansion tank needs to be sized for the system capacity, plus the operating pressure of 17psi

The expansion tank pre-charge would need to be adjusted to match the fill pressure you decide on. Here is a link to a expansion tank sizer.

I remember

@ July 7, 2014 3:52 PM in Cleaning radiant tubing

A micro jetter is what we need to develop!

Something with an 1/8" flexible line that could pull itself through several hundred feet of pex. Heck doctors push tubes through our veins and can take pictures and do some sampling even.

storing energy and delta Ts

@ July 7, 2014 3:33 PM in Peer review please...

Lets assume you could get 130F from a black colored pad, and you had insulated storage in the ground to leverage that fairly consistent ground temperature.

140F in a tank of hot water in the ground at maybe 60F, so an 80° ∆T grabbing at that stored energy.

With a block of ice, say 20°F in 60° ground, only a 40° ∆T.

With ice you could get ac with dehumidification, as you have a cold enough temperature to condense.

In the Viessmann approach you transfer this energy with solar assisted heat pumps, no boiler comes close to the efficiencies the heat pump can. And the energy to run the HP could be with a PV array, that also could be also offsetting the buildings electrical loads.

The PV array, maybe more of the system, qualifies for rebates, utility buybacks, or adding to the community solar garden.

I just don't see solar thermal, even with the most efficient fossil fueled boiler back up coming close?

I've been a die hard boiler and thermal guy all my life, but you cannot deny the HP and inverter technology when looking into the future.

The Chiles boys did some pool deck recovery systems around here many moons ago. not sure if they are still operating, may have been solaroll systems?

My next heat pump may be the size of my microwave, and an energy fence for my loop field


@ July 6, 2014 1:19 PM in Cleaning radiant tubing

start with boiler fill pressure 12-15 psi, that way nothing needs to be isolated or taken out of the circuit. Disconnect one side of every loop at the manifolds, see if they all flow. If you have some that are not flowing I would use higher pressure. Start with house water pressure, still no flow, go with high pressure.

I have had good sucess with this method, plenty of RadiantRoll and early Entran here in SW Missouri, home of Heatway :)

There were several jobs that loops and entire zones had to be abandon, plugged solid.

Heatmeister out in Colorado is the "meister" of radiant flushing, he has developed methods and tools just for this purpose.

A pressure pump that pulsates might be a good method. I remember installing and servicing the old SoftSpray car washes with my dad. They used a single cylinder piston pump that would pulse the water spray. They did move the dirt along better, but those recriprocating pumps needed frequent repairs, and were crazy loud to work along side of.


@ July 5, 2014 1:57 PM in Cleaning radiant tubing

what you probably have is iron ferrite sludge. it is common in non barrier tube systems. Depending on how long it has been running and how much O2 has been pulled in will determine how tough it will be to clean.

In some extreme cases the tube can sludge so badly that it cannot be salvaged. The small diameter RadiantRoll and TwinTran tubes can be a bugger to get flowing.

Determine if the loops flow at all. If so a good pressure flush can usually clear them out.

You may want to isolate or disconnect the boiler from the piping, generally they do not handle pressure over 30 psi. Isolate the expansion tank also.

All the rest of the components should be rated for 150 psi, and it may take all of that to free up some sludged loops.

Once you get all the loops and piping flowing you could add a cleaner like the Rhomar.

None of the hydronic (soap based) cleaners will dissolve the iron particles, if that is what you have in the system, pressure is what it takes and lots of water flow to move the heavy particles out.

In some cases systems plug with lime and minerals from constant water make up due to a slab leak somewhere. To clean a limed up system you need a mild acid product like Hercules Sizzle or other brands.

Once you get it flushed and flowing, isolate with a HX as you mentioned and still add a magnetic separator to catch and capture any remaining iron ferrite that may still linger.

All non-ferrous components on the tube side, of course, when you repipe.

you're on the right track

@ July 4, 2014 10:04 PM in I can not get my head around the over sizing of boilers

Thermal Equilibrium is what you are noodling. Here is a link to some good reading on that and heat transfer in general. page 51 talks about your question. It's really the heat emitters, not the boiler that drives the thermal equilibrium.

info on slab temperature

@ July 4, 2014 9:46 PM in Peer review please...

Probably not as warm where the tube would be located, but even 100- 120F would be a good amount of energy to add to 55F potable water to pre-heat DHW.,

In reality the average household spends 300 bucks or so per year for DHW, so the DHW summer load is not what you want to chase. Wind and cold temperatures would make the outdoor slab a non-starter for thermal in all but the hot summer months.

I found a really detailed German study on outdoor slabs for heat exchangers, lots of technical data, I'll look for the link again.

I'd imagine Viessmann has researched your idea also. But after seeing that large ice storage device at ISH last year :) I don't think you can store the thermal energy efficiently and affordably to make the numbers work.

Perhaps that is why Viessmann is looking at ice storage in the ground not high temperature water?

Certainly the desire for Europe to move away from Russian oil drives the heat pump concept, but properly designed and applied it's tough to beat a heat pump. Spend all the extra cash on a PV array large enough to run the heat pump :) Here is the link to the ice storage device they had on display at ISH.

do you have

@ July 4, 2014 9:29 PM in Pump Exercise

a good dirt separator or Y-strainer? It might be a better investment for the system overall instead of an exercise program.

A good dirt separator will take particles down to a 5 micron out of the fluid. Use one with a magnetic fun to to handle and iron ferrite. Good for pumps, valves, boiler, and all heat exchangers.

here is a course

@ July 4, 2014 8:06 AM in Getting into mod/con business

that will be right up your alley. Roy will present a generic and in-depth mod con class. he does a great job explaining combustion in everyman language. Online courses make it very easy to learn.

Plenty of other great classes at this school also.

sounds like plenty of exercise

@ July 3, 2014 9:28 PM in Pump Exercise

if the pump in question runs daily to provide DHW via the indirect? You really don't want to run a pump that could pull heat energy from the indirect, either.

Be sure you have good check protection on the indirect, it can easily thermosiphon heat back into a cold boiler. I'd suggest hydronic specific spring check. Soft seat, tapered plug, low "pop" spring and bubble free seal.

fairly necessary

@ July 3, 2014 5:37 PM in True RMS

if troubleshooting modern HVAC controls and equipment. I know the output from the triac relay on many solar controls cannot be read accurately with a non RMS meter. Worth the extra bucks I think.

A good RMS explanation here from Extech

for what reason?

@ July 3, 2014 12:53 PM in Pump Exercise

do you want to exercise them? To prevent them from seizing up over non-use seasons?

I know Grundfos has a little "tickler" built into the pumps to help wake them up after long shut down periods.

Usually the biggest cause of stuck rotors is bad water quality, in closed loop applications it is best to use a cleaner, good water, and a hydronic treatment chemical. That would protect all the components in the system valves, pumps, boilers and heat exchangers.
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