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hot rod

hot rod

Joined on August 27, 2007

Last Post on September 1, 2014

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excellent info

@ September 1, 2014 4:45 PM in Free Publication on Corrosion Prevention

thanks Roger


@ September 1, 2014 3:54 PM in two different metals

from that UK site mentioned


@ September 1, 2014 12:28 PM in two different metals

It's the O2 that is needed to support corrosion. In a closed loop piping system the goal is to eliminate or control the O2. That is why inhibited glycol and products like Fernox and Rhomar are so important, they control the O2.

This is the main difference between hydronic and plumbing systems. Plumbing, open loop, systems see fresh oxygenated water, so it is important to address dis-similar metals.

Once you eliminate the O2 from hydronic systems, assuming no additional air (o2) is allowed in, very little potential for corrosion.

Remember learning this lesson with non-barrier plastic and rubber radiant tube?

Some corrosion is good, it provides a protective layer to protect the metal. Anodized aluminum is really "rusted"

Hydronic inhibitors and inhibited glycols contain film providers as part of the blend. A very thin protective coating is on all the components to prevent corrosion.

Some good reading here, plenty of experience in the UK with corrosion as they still use open, expansion vessels in many heating systems.

true that

@ August 31, 2014 5:10 PM in hot water demands

inn today's low heat load homes, the DHW load can be much larger that the heat load. The boiler needs to be sized to the largest load, regardless.

But oversizing a boiler just for DHW may lead to in-efficient short cycling during low heat loads.

I'd agree in many cases with large DHW loads and low heat loads a tankless sized to the DHW might be the best match.

what size boiler?

@ August 31, 2014 5:05 PM in I don't have 18"

If that is a 64,000 BTU/ hr hot water boiler you could use much smaller pipe, check with the installation manual but 1" pipe should easily move 6 gpm or so.

1-1/2" pipe needs around 11 gpm flow rate to assure 2 feet per second. You want 2-4 fps to be able to push or pull the air around the piping loop.

It's all a guess

@ August 31, 2014 2:36 PM in hot water demands

until you define EXACTLY how many gpm those 3 showers can flow. There is a big difference between a 2.5 gpm shower head and a 9 gpm or more body spray. Times 3!

If the homeowner cannot tell you how many gpm they need, want, require You tell them what your proposed system is capable of supplying, and have them sign the proposal.

In some cases a large dump tank 120 gallons at 160F with a thermostatic valve is best.

Low flow requirements IF you have enough boiler HP a small indirect piped to move the boilers entire output may be enough.

Asking for three 20 minutes showers running at the same time is settting someone up for failure, don't let it be you.

Use the power (math) Luke Skywalker.

sensor location

@ August 31, 2014 9:09 AM in Viessmann Temp Sensor w/ Caleffi SEP4 Hydraulic Separator??

we show both locations with the separator, in the latest Idronics 15. If you install it on the pipe, be sure to insulate it. I would still use some heat transfer paste.

With both the boiler and system circs running, depending on flow rates, you will get some temperature blending in the separator. I prefer sensors in a well, but the sensor on the pipe downstream would read the "blended" temperature.

Another tip if you ever need to install a sensor on a bolt or pipe is to get a screw lug from an automotive or electrical supply. The early solar tanks had a stud welded onto them for sensor mounting.

depends on how many

@ August 30, 2014 11:12 PM in In-Joist, Hung Pex, Planning Manifold Connections

joists you are pulling down through. 1-3/8 can be tough to pull more than 4-5 joists, so I used 2-3/8" holes. as long as the joist dimension allows it.

The only time you need to drill the far end is if you come up short. Then the next loop needs to go down the the far end, cross over to fill that bay.

Here is a link for hole drilling in structural joists. Check with your local codes, generally a 2-3/8 inch hole can be drilled in 2X8 or deeper joists, stay out of the middle 1/3rd.

If you have engineered TJI type joists, use their hole drilling guide lines.

looks like

@ August 30, 2014 10:45 PM in Viessmann Temp Sensor w/ Caleffi SEP4 Hydraulic Separator??

a 6mm diameter sensor? about 1/4" bolt size? There are a few different well sizes out there, most US size thermistors are larger 1/2" diameter. The Euro stuff and solar sensors tend to be 6mm.

How close does the sensor match that well?

For sure, use some heat transfer paste, or silicone acoustic grease in the well.

It's easier to find small tubes or bottles of the acoustic paste sometimes.

3 loops

@ August 30, 2014 9:53 PM in In-Joist, Hung Pex, Planning Manifold Connections

would require 3 sets of holes, space them 12 or 16" o.c. or whatever the design calls for.

So the first loop traveling the farthest may only cover two bays, the 2nd loop three bays, maybe 3 bays for the 3 rd loop.

The loops need to be the same length, sometimes a loop only goes part way down a bay, before you need to head back to the manifold so as not to exceed the loop length.
Bring the next loop to meet that end. In that case drill another hole at the other end of that joist bay, bring the next loop down to meet the shorted one.

3/8 or 1/2' pex?

@ August 30, 2014 6:22 PM in In-Joist, Hung Pex, Planning Manifold Connections

"sew" it through the joist. Take the free end down through 2-3/8" holes, turn around and come back to the manifold.

Fasten that end solid at the manifold. Put a screw right trrough the pex to a joist so you don't yank the manifold.

Then pull the loop down to the end of every joist bay, fasten the loop end and work back to the coil.

You need to calculate how many bays your loop length will cover so you start in the right bay.

If you have multiple loops, start at the one most remote.

You may need to drill a few sets of holes, depending on how many loops.

Some fasten the runs below the joist instead of drilling holes, looks cheesy to me.

If you have TJIs you need to refer to the hole drilling chart to see where you are allowed to drill, same with joists. You need to be a certain distance from the bearing point for the holes.

Google that hole size and drilling location for whatever joist you have.

goes better with two people to prevent kinking.i

ECM circs

@ August 30, 2014 9:48 AM in rework closed loop to drainback

are another option if you have 120V. Maybe pump that system with17W on the Alpha.

On dual pump, high lift head, drain back I have paired and Alpha with a 15-58. Start the siphon with both running and drop back to the Alpha at speed 1 or 2.

Could be

@ August 28, 2014 10:33 PM in Boiler Mate WH7L Noise

That coil is limed up. Has the recovery time slowed for noticeably?

Same experience

@ August 28, 2014 10:28 PM in Granite steps snowmelt

You really need three tubes on the tread to do a good safe melt. One tube close to that front nose of the treaded or you get an ice build up there. I have also seen installers Run PAP up and down instead of across the tread 6" on center. Takes patience, I think John Abularage in up NY does his steps that method

I doubt tube under 8 " of anything would do much melting. Maybe if you ramped it up starting in June🔥

Lower the lift head

@ August 26, 2014 9:45 PM in rework closed loop to drainback

By raising the drainback tank as high as possible Those DC solar pumps are not available in a wide selection

it must have

@ August 22, 2014 5:30 PM in Rate my boiler setup

a pair of closely spaced tees to be primary secondary, or a hydraulic separator (low loss header).

In this Lochinvar installation drawing the boiler has a piping circuit that leaves the boiler, crosses thru those tees in the bold highlighted box, and back to the boiler, the primary loop. The boiler pump, the black one in your pic, has to be in a loop.

I can't quite see enough of your boiler piping to tell, a drawing may be better.

If it is not piped P/S, the boiler circ and the zones circs will be in series, basically doubling the head, not the best piping method, or what the manufacturer is trying to show.

If you do not have a pair of tees piped 6-12" apart somewhere in the piping you do not have P/S piping.

installation manual

@ August 22, 2014 10:42 AM in Rate my boiler setup

check that piping with the suggested piping in the manual. Download one from Lochinvar site if you do not have one on the back side of the front cover.

Looks like an attempt at primary secondary piping?

As far as the non barrier tube, consider adding a conditioner, Rhomar or Fernox corrosion inhibitors would offer some excellent protection.

good points

@ August 22, 2014 9:19 AM in condensate drain ?

It's at my mother in laws, age 84, very clean household, no pets, all hardwood and tile flooring :) I do replace the filter twice a year 1" pleated type. I'll look for leaks and check the blower wheel condition , thanks.

I don't mess with air side stuff much, so I don't have a reference, my other two run clean pans is all I know.

the only trap

@ August 21, 2014 5:05 PM in condensate drain ?

is below the concrete slab, a basic floor drain. The horizontal 3/4 PVC condensate line stops at that floor drain, it is not into the water seal at all.

There was a 3/4 PVC running trap where you see that tee and stand pipe. The tech said it did not need to have two traps.

It is an upflow so that coil is in positive pressure.

If the manufacturer states it is alright for the coil case to rust away, I'm tempted to build another drain into that pan that allows all the water out, not allowing 1/2" of standing water.

It just seems like that coil should be elevated above the standing water, or have a plastic bracketing that would not rust away?

I have two other AC coils and neither of them are rusting like this.

floor drain

@ August 21, 2014 12:33 PM in condensate drain ?

directly below the unit. i had the sheetmetal guy make a heavy gauge pan the size of the closet floor, I sealed the pan to the floor drain, like a shower pan. Glad I did there is hardwood floor around this closet. The old system leaked and destroyed the flooring.

The 3/4 condensate line drops straight down and over 2 feet to the drain, plenty of slope as I had them install the AH up on plastic feet.

The tech removed the condensate trap yesterday, as that is where it plugs. He put in a tee and a stand piece where the trap was.

Plenty of humidity here in Missouri, so much water.

I'm fine with the water in the pan, just concerned with the galv steel A coil frame rusting away sitting in that 1/2' of water.

thanks all

@ August 20, 2014 10:13 PM in condensate drain ?

this system was installed two years ago.

The pan is plastic. I question why the metal case around the A coil sits in the water. If it were elevated I would not have the rust and corrosion.

It plugged the drain the first year, I contacted the installer, rep and manufacturer. I will try the rep and manufacturer again, this doesn't look like a long lasting product, not to mention the potential mold issue.

condensate drain ?

@ August 20, 2014 2:49 PM in condensate drain ?

This pan lies with about 1/2" of water. The drain connection is about 1/2" from the bottom so the water never drains completely.

Twice now the drain line has plugged with the rust sludge, which trips the high level switch.

It doesn't seem like a very good design, and the A coil bracket is rusting away.
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