Heating Help

You're always allowed to disagree

@ December 3, 2009 1:40 PM in Conflict over Heat source.

but a couple of things.

1. I would never claim that a water heater was in the same league as a mod/con boiler. Jumping from the 75-80 to the 95+ range, plus going from atmospheric to sealed combustion, results in real savings. It's just that, if your heat load is low enough, even those savings may never be economically justified. Ever. at 15kBTU max loads, unless the client is in alaska or a severely cold climate with lots of degree days, he's probably in the boat of "hey, a modcon would be nice, but it will never pay back". and it also would not run at 95% efficiency when it would be below min mod all year.

an electric heat source might be "100%" efficient, but very few locales would find operating an electric boiler on part with a 75% to 80% efficient tank heater. Even at 60% gas will run circles around electric in many locales. but that depends on local fuel rates. Same deal for electric mats... for very small areas or very low loads, maybe. but at 15kBTUs/hr, I doubt this area is one of them.

2. You hacked that water heater to do nothing it was ever built to do. I am not assured that adding a reset control to the tank heater was a good choice and I would not assume that it was operating well.

3. It's not hard to beat a home cheapo special. A basic sealed combustion water heater is still inexpensive and would negate a lot of the differential between an atmospheric unit and a sealed combustion mod/con.

If you like fresh air in every room

@ December 3, 2009 10:10 AM in Use minisplits for HRV or ERV?

you need to make sure fresh air gets to every room.

hmm.

@ December 3, 2009 10:08 AM in Conflict over Heat source.

2 mixing valves, 3 pumps, electric instead of gas.

unless your electricity is cheap, I think they would be better off with the tank heater and an injection mixing control through the HE. both now, and later.

if electricity is cheap, then go nuts, but what's with all the mixing valves, do you really need 3 temps? this would be a really nice place to use an ECM pump and zone valves... no minimum flow requirements for most electric boilers.

Scott

@ December 2, 2009 2:34 PM in Conflict over Heat source.

you're judging the whole class by a bad install. You can trade horror stories about every heat source in existence, but just because people don't know how to size DHW tanks and heating appliances doesn't mean they can't, and don't, work.

they can work. and they do. But with all things, if you don't know what you're doing, then you can get burned. which is why reputable people do things like L'Town here did, and try to get info before they do something new.

this is not a big deal.

@ December 2, 2009 2:27 PM in Conflict over Heat source.

the water heater will run about 75% to 80% efficient in a heating app. Not that bad. Much better than the "EF" would indicate. though you are reducing your DHW performance as well, so you better make sure the tank can do both at once.

Use an injection mixing control on the heat exchanger. cheap upgrade there.

why check valves on your zone valve loops? that's pretty unnecessary.

the only thing I've ever seen bite anyone here is either bad HE sizing, or if the sensor on the tank is in the wrong spot you can get a runaway tank demand. with injection mixing, water back to the tank can be as low as room temp, huge dT, and if it passes the sensor on the way back into the tank, it fires. and fires. and fires.

I've only seen that once. So ideally you'd use a unit with separate taps, but we do what we must.

a Taco X-block works too, though we having some problems troubleshooting one right now generally it makes the install pretty simple if the system pump in the unit will do the job, which it should if the water heater will. I prefer separate and standard components (two pumps anyone would have on a truck, a 356 which is the most common controller in the world, and a plate HE... pretty easy to service).

as charlie says

@ December 2, 2009 8:20 AM in What's the sq.ft. EDR for modern rads?

I would use the EDR conversion to figure the output of the existing rads, and use the MFG data/correction factors directly to figure output of the new rads.

well

@ December 1, 2009 1:46 PM in Prestige with Alpha pump

I have no idea how you'll get an outlet wired into the cabinet of the solo, but the other trick is you would have to maintain the minimum flow rate requirement for the solo. that can be hard to ensure with "autoadapt" but with fixed pressure and adequately large minimum zones or pressure bypasses it can be done.

I would question the wisdom of it though. If you can do the whole system with one pump and it has to be fixed speed, that's not a bad place to be.

8" o.c. is typical

@ November 24, 2009 10:40 AM in Staple up radiant

Screws or heavy staples work well, no silicon if it's a good plate, tubing should fit tightly, do not affix loop heads or bends on either end.

staple up can work

@ November 22, 2009 4:40 PM in Last Minute Staple-Up - Radiantec Question

but lightweight plates are not in the same league as heavyweights. They may have tried to test it. In good faith, they may even be reporting what they think is the truth. But I think they are pretty clearly wrong, based on the collective experience of our industry over the last ten years. The difference, in the field, has not proven to be "close" as far as we can tell at all.Their commentary on how pipe size had almost nothing to do with the increase of output going from 1/2" naked to 5/8" plates (on their plate discussion page) I found amusing, since for 30 years they have been pushing huge pipe claiming it had "double" the output. apparently "double" isn't much. and in their defense, "huge" dropped from 7/8" to 5/8" not too long after they started doing some installs themselves... maybe in another 30 years they will join all the rest of us with 1/2" or 3/8" pipe!In short: they are certainly not scientists. I would not accept any "testing" they have done as rigorous. And in the case of lightweight plates vs extruded plates, I think they are in left field. Deep left field.

when I read your post

@ November 22, 2009 8:48 AM in Thoughts on variable-speed pumping and air removal

I thought immediately... people really do the 2 ft/second minimum?

those of us in radiant don't, ever. that would be over 1 GPM in a 1/2" PEX loop, and very few people are using that as a minimum per loop. Heck, I'd say I almost never hit 1 GPM/loop.

with a microbubble resorber, we have had no air problems on any systems other than non-purging, no-flow situations or system leaks. I don't expect to see any on the variable speed pumping systems either.

that's all nice and all, but really...

@ November 18, 2009 9:13 AM in What is so special about the Viessmann Vitola?

it's just one thing.

40 gallons of well insulated, built in buffer capacity. good stuff.

need to retract my rumour

@ November 17, 2009 9:31 PM in Will heat pumps someday run hydronic systems all winter?

I misinterpreted some of the sketchy info I got on the Altherma. It is claiming 131 degree max temps, but I can't really believe that at face value... digging more, but I suspect that upper temp range includes significant "backup" heating from the onboard electric backup. but that is just my speculation...

no problem

@ November 17, 2009 1:48 PM in Roth Radiant Panels, PEX-al Tubing vs pex expansion rates

we use Mr. Pex PAP in Roth.

thanks

@ November 14, 2009 8:40 AM in Subfloor panels

it was a good project all around for us and for Ed Reynolds who is a top notch installer, troubleshooter, and generally great guy all around. We love working with him.

maybe

@ November 13, 2009 11:42 AM in Will heat pumps someday run hydronic systems all winter?

we are looking at the Daikin Altherma for our shop project and for a client as well.

details are currently pretty sketchy, but it claims output down to -4 Deg F. I'm not entirely clear on what the performance is at that level... first blush seems to indicate 77 degree water at that outdoor temp, something like 95 degree water max.

Most buildings will struggle to utilize temps that low, but uncovered slabs with heavier tubing density, and/or any low temp radiant baseload with an air handler backup could probably make good use of such a unit.

but it certainly isn't going to replace boilers soon. for high temp apps you'd need to have a seriously huge delta-t and use this as a booster.

If robur or others get natural-gas powered heatpumps optimized for smaller loads, you might see some serious inroads there. or if the electric powered units get a bit more aggressive at lower temps. Or, maybe they will follow their air to air cousins and become the shoulder season heater for hydronic systems, transferring to a boiler during very cold weather.

they will definitely fill a niche! but I don't think combustion is dead just yet. 20 years from now and a few more technological leaps later... maybe.

depends on the boiler

@ November 12, 2009 11:23 AM in aquapex for heating

Triangle Tube says you can use open oxygen systems with their boilers. the 110 solo an excellence have cast iron pumps built in that need to be replaced, but otherwise, no problem. make sure you don't use cast iron outside the boiler.

raupanel is good

@ November 10, 2009 8:49 AM in Subfloor panels

if you're doing your own labor, you can also make your own with Thermofin "U" plates and plywood.

Not sure how you're going to do anything to "pick up R-value" over roth though..?

not really

@ November 10, 2009 8:47 AM in Insulation for radiant heating between subslab and cast surface

bubble wrap isn't really insulation. anything with foil will be a waste of time and money here. Never use Bubble anything, ever, for any reason... and under a slab, never use anything with foil or calling itself a "radiant barrier". they are ALL junk products.

nothing under 1/2" is much for insulation.

The minimum measure I would take here is 1/2" of rigid foam (or "The Barrier", which despite the name is actually a foam product) with wire mesh on it to tie the tubing to. and that would hope that your slab isn't a huge source of heat loss: depending on where you are I would use much thicker insulation.

You can also use something like Roth Panel which is either 3/4" or 1" thick, has real foam insulation and an aluminum top layer for tubing attachment built in. then you float a finish floor over it. you can get total building under 1-3/4" pretty easy that way, and get something more like actual insulation under it.

not that I've seen.

@ November 10, 2009 8:41 AM in radiant thermostat

you can see the outdoor temp, control floor temp, and give air temp control too with a tekmar 542 with a floor sensor and outdoor sensor attached.

but the outdoor sensor won't change anything. it will simply maintain the room temp you have set, with a minimum floor temperature.

typically

@ November 10, 2009 8:37 AM in buffer tanks ,ODR and mod cons

we put it on the boiler supply line before any loads are satisfied to make sure we have to raise the whole tank temperature before satisfying a demand.

Basically, it's a short, VERY FAT pipe. one in and one out. Since we do many systems without primary/secondary piping, especially on systems small enough to require a buffer tank, I do not want to add an unnecessary pump and I also don't like mixing boiler return with boiler supply OR radiant supply with radiant return, both of which would be counterproductive from a water temperature/efficiency standpoint.

we typically pipe them upside down as well (hot top cold bottom) if they are tall enough to care, so we are pulling colder water at first for some period of time (perhaps not long, as pumping can kill stratification pretty quick) on a cold start.


my kingdom for an affordable 10 to 20 gallon buffer tank with 2 x 1" taps and no additional frills, or with a microbubble resorber built in (not an air vent) perhaps. Wall hung and dimensioned with a tap on each end. and by "affordable" I mean "cheaper than a small electric water heater at home depot" or at least the same cost and nicer looking...

we are using buffer tanks a lot

@ November 6, 2009 2:35 PM in buffer tanks ,ODR and mod cons

and we simply pipe them inline, more times than not, so we do not cross mix the return water with supply water and sustain cold returns as long as possible. and, if you don't need primary/secondary, it doesn't add a pump to do this.

physics

@ November 3, 2009 3:32 PM in Radiant Boiler Sizing Choice

lower minimum modulation is better. definitely. no question.