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Joined on August 20, 2009

Last Post on February 28, 2014

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Hard Grey buildup in radiant system

@ February 28, 2014 5:39 PM in Hard Grey buildup in radiant system

I have a client who is getting a hard grey buildup in his radiant system, making valves stick etc. it's o2 barrier pipe, geo system with a buffer tank, fully closed and when they close the makeup valve there is no pressure drop, so no leak.

I'm kind of astounded at how much buildup can occur apparently from the single fill of water... admittedly, it's probably about 200 gallons of water, but still.

buildup is hard enough to require chiseling with a screwdriver to remove.

anyone else ever seen such a thing? client will send out a water sample for testing but would love to hear if anyone's seen it before.

what kind of radiant is it?

@ September 10, 2013 9:56 AM in Radiant schematic

if it really needs the same temp as the baseboard, you could use reset on all of it.


@ September 10, 2013 9:55 AM in Primary/secondary piping

IF the primary loop will run for anything other than this zone.

if this zone is the only thing running, I would be looking hard at why I was doing primary/secondary in the first place.

it's not about efficiency

@ September 6, 2013 3:14 PM in High efficiency gas boilers

I think the ratings with firetubes vs others are the same. I like them because they are stainless steel, low pressure drop for water pumping, higher water content to reduce cycling, wider passages that won't plug, and generally simpler to service. I.E. they are robust.


@ September 6, 2013 11:21 AM in Am I rolling the Dice with Kitec here?

your garage and basement numbers are at least twice as high as reality would allow for.

wood over roth?

@ September 6, 2013 11:16 AM in Solid vs Engineered Hardwood for Overpour

they require sleepers for that. did you do it without sleepers hot rod?

generally speaking

@ September 6, 2013 11:11 AM in High efficiency gas boilers

you'll save enough to buy a new boiler in most cases in significantly less than 15 years.

Cast iron boilers can fail in 15 years too. we aren't living in the 60's anymore. manufacturing got lean all around.

I will second the enthusiasm for "firetube" series boilers.


@ September 4, 2013 8:07 PM in Searching for Oil Boiler

look into pellets in your area if you are ok with emptying ash once in awhile.

here in maine it can literally cut operating cost in half. don't see why it would be different on your side of the boiler. need a place to store pellets and a good supplier of course.

variable tube spacing

@ September 4, 2013 8:04 PM in Radiant Floor Help

matters more the less conductive your radiant media. with slab, it matters. concrete is not as conductive as aluminum. with continuous full thickness aluminum across the top of a panel, with excellent tubing contact in the groove, it doesn't. the apparent conductivity from pipe to any floor point is not very different in that case.

Are you doing 18" o.c. in a garage? that's wide for foot comfort in a residential space is all.

I'm with SWEI

@ September 4, 2013 10:53 AM in Searching for Oil Boiler

oil is kind of a dead end. and your heat load is REALLY high.

I would consider modern cold climate air source heat pumps in larger areas (great room, etc) and oil backup.

Pellets would be great too if you don't mind being a little involved with your heat source. easily cut your definitely significant operating costs in half.

I have no idea

@ September 4, 2013 10:44 AM in Radiant Floor Help

where your complex comes from, but I'm just talking math here. If disagreeing with you means I have a superior attitude, so be it. Your comments indicate that your understanding of these issues isn't as solid as you seem to think it is though, so maybe you should consider upgrading your walls from glass before you start throwing those stones.

1- of course heat loss matters. the higher the heat loss, the higher the water temps you need. with weaker panels the water temp you need goes up faster than with more conductive panels. If your heat loss is low, the difference between panels is lower. Saying heat loss doesn't matter is factually wrong. And it's not housewide heat loss we're concerned with here, really, it's the worst heat loss in the house you're heating with the radiant in a room by room calculation. No one can answer that question without doing the math. I work on supergreen projects that still have individual rooms with lots of glass and high heat loads, and you still have to meet those loads, so that means turn up the water temp or add supplemental.... moreso with weak panels than with strong ones.

2- you need more zoning with wider water temperature requirements from room to room. weaker panels have wider water temp variations than stronger panels across different heat loads (flatter curve). whether this changes anything on your project cannot be known by some guy standing at a computer in maine without a floorplan. Just noting it's a consideration. If you zone really heavy in all cases whether it's needed or not, then this probably won't change anything for you. Of course, you're not the only one who will ever read this thread.

3-I prefer single temp systems too. it's a lot easier to keep them single temp with a narrower water temp variation, which is affected by loss, floor covering and panel choice. again, weak panels vary more widely and more often require multiple temps. again, no idea if it applies to any of the 10 houses you will do this year without doing the math. but it's a concern. and of course, you don't know if it applies either, right now. sounds like you aren't even doing the math to tell if you need this or not, so hey, good luck.

4-I was talking about finish floor resistance, not plywood under the aluminum. the plywood under the aluminum isn't worth thinking about because of course we are all insulating properly under our radiant panels, right? even 1" of plywood won't change your insulation strategy or your downward heat loss by any significant amount.

5- 8" spacing does NOT always require lower water temperatures. this is your biggest misunderstanding of all. the HIGHEST AVERAGE CONDUCTIVITY from pipe to floor surface has the lowest water temperature requirement. You can help a weaker panel in this regard by tightening tubing on center so each point of floor surface is closer to a pipe (less resistance between the two). but warmboard's aluminum is quite sufficient to do the same thing at a wider on center. the weaker panels do not. does your $2.25/sq ft between the two include the +50% pex/manifold cost differential?

6-the Rate of heat transfer is measured in BTU/sqft/hr. that's the potential output of the floor. the rate is different for more conductive panels rather than weaker panels because they can conduct more heat to the floor surface faster. that's why these methods are better than suspended tube, for example: the rate suspended tube is capable of is much lower. the rate warmboard is capable of is higher than less conductive panels.

Sunboard, for example, publishes some really half hearted output chart on some Loopcad template on their website. they don't label it very clearly but it appears that their panels put out 15-18 BTUs/sq ft/hr at 110 degree supply water. I presume that's for wood floor finish but they don't say. I can beat 25 BTUs/sq ft at the same temp with warmboard. that's the difference good aluminum makes.

sunboard may be very adequate for your projects: I don't know because that requires job by job analysis for me to say. Certainly you have some projects that are better suited for it than others. I'm not saying you shouldn't use it or that you are causing any problems on your systems.

but I CAN say your reasoning, at least, is mostly wrong. If that makes me "superior", I can live with that.

hardly matters

@ September 3, 2013 9:12 AM in Radiant Floor Help

.007 is still significantly thinner than the lightest gauge aluminum we'd ever use in a plate. .002 is basically useless other than to help prevent heat striping.

I don't know if it would be worth it or not. I don't know your heat loss or the impact of whatever the water temperature differential would be on your efficiency, need for supplemental heat, number of mixed water temps, or zoning. I would be skeptical that the "all in, apples to apples" price difference is so high on any but the absolute largest projects.

You can "transfer heat into the space" with anything. the question is, at what water temperature and how fast, and where does that fall along the lines of your particular project's needs? certainly there are times that the performance differential won't be as import... i.e. less resistant floor coverings and lower heat loads. that's a completely valid analysis.

but don't pretend they are the same. they are not.

you're not correct

@ August 31, 2013 11:04 AM in Slab overpour "Radiant Green" hydronic heating panels?

that the only R that matters is the R under the tube. the tube are is only one part of a heated slab. the r value under the tube matters somewhat, but the overall R under the panel matters much more. if you have a 1/2" out of, say, 9" that is 10 degrees hotter and has a lower R-value, computing how much that matters is fairly simple math, and it's not a lot. you still get the target R-value under 17/18ths of the slab. but I don't believe radiantgreen under slab panels have a recessed pipe, instead they have a knob configuration panel.

That said the previous comments by the radiant green fellow in this thread don't exactly inspire a warm feeling of confidence in their understanding of heat transfer. "nowhere to go but up"? really? that's premium grade sales talk right there.

start temp depends on

@ August 31, 2013 10:50 AM in ODR Starting Temperature

your boiler firing differential and your emitters.

Your absolute minimum start temp must be greater than the boiler firing differential plus room temp. so if the boiler is set to start at 80, with a 20 degree firing differential, and you have a 70 degree room temp, it won't fire until the water comes back at 60... unless it's a "split differential" where with an 80 target it fires at 70 up to 90 for an 80 average. Gotta know how your control works there.

for convective baseboard I usually bump it up to a 90-95 minimum regardless

not necessarily

@ August 31, 2013 10:39 AM in Insulation for Pex?

I had a cast iron boiler in my house that died after 12 years. New school cast iron isn't like 50's cast iron, they have been value engineered for 50 years since the earlier "overkill design" days.

a new mod/con with firetube, stainless steel HE should last a good long time and will easily cost justify itself over a cast iron, on any significant heating load. they are installed routinely with few problems these days. looking at the triangle tube as one example, it's basically got seven parts in it. service is not complicated. other firetubes are likely to be similar in that regard.

the only app I can see where cast iron is justifiable is if you have a sealed combustion option for it and you have a fixed, high temperature heat demand. as soon as you bring in reset, the mod/con should be a clear winner in any comparison. sealed combustion is good for some efficiency bump regardless of any other benefits as well, and it's one that isn't captured in AFUE.

I have a chunk of sunboard here on my desk

@ August 30, 2013 11:39 AM in Radiant Floor Help

and that aluminum is NOT the same level that warmboard is at. it's very thin and flimsy. This panel is better than most of the knockoffs out there, but I highly doubt it's got the same performance characteristics as warmboard.

if you're running temps like that

@ August 30, 2013 11:30 AM in Insulation for Pex?

I'd recommend PAP (Pe-Al-Pe) to avoid excessive tubing expansion and sagging. the aluminum core will help its stability.

while I agree

@ August 9, 2013 10:51 AM in Solar Thermal is Dead

right now in america you cannot cost justify anything against natural gas. what is the value of that comparison?


@ July 31, 2013 9:34 AM in Chilled ceiling design

even the smallest valance unit is sized for real cooling loads so unless you have a very large area it's unlikely you can just dehumidify with it without also doing some significant sensible cooling.

Typically this is handled with very low flow chilled water coils in the ventilation system, or standalone dehumidifiers, or chilled fancoils with reheat. I prefer the vent coils.

I would choose

@ July 6, 2013 5:57 PM in mixing strategy

none. within 20 degrees I would not normally recommend mixing. ESPECIALLY if:

1. lower temp has mass and good thermostats that can use predictive logic (PID, PWM, feedback) to control it.

2. lower temp is in a lower priority situation such as a basement or garage where either loads rarely change or absolute precision is not necessary.

we hate the iSeries valves.. they are really built for continuous circulation setups.

if it bugs you, bump your highest water temp area to a 10 degree dt and your slabs to a 20 and you'll even yourself out by another 5 degrees or so.


@ July 6, 2013 5:53 PM in Best pex for warmboard

generally recommend PAP. tighter fit, better conduction, better at staying put.

I would always

@ July 5, 2013 11:08 AM in Loop length?

advocate for being able to flow balance/adjust individual rooms. equal loop lengths only matter if you are not going to have balancing capabilities on the loops. and I think that is a bad idea.
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