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Joined on October 13, 2004

Last Post on April 18, 2014

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Thermal shock

@ March 4, 2014 12:04 AM in Help!! staple-up insulation foil myth

Not over my head. Depends on how your system is set up. Staple up is what you have. What temps are you supplying? Is it zoned? Usually it happens when a certain zone is turned down to bare bones and the boiler is up to temp maybe coming off a call from another zone. Boiler is hot cold zone calls, and bingo bypass piping only helps a little.
So the boiler can be a cold start boiler, and still get thermal shock in certain scenarios

If your boiler is suffering from excessive condensing then there will be metal flakes in the pan below the burners, and on the burner tubes. Don't know your service regime annually or otherwise. Has it been serviced periodically?

If your boiler is plumbed according to WM I/O manual then point that out to the buyer, and inspector. If not they may have a point.

I will say

@ March 3, 2014 6:49 PM in Help!! staple-up insulation foil myth

That this home inspector is being thorough good for the buyer.

Last year a friend of mine bought a log home with all kinds of trouble......and had a home inspection for 400 bucks. When i asked what the home inspector said about the issues in all facets plumbing, structural, electrical .... My friend said all the inspector said is this house will be a lot of work.

About the low boiler return temp boiler shock would be what the inspector may suspect. If in deed there has been thermal stress over the last 10 years it would be leaking by now.

Simple boiler bypass does not always guarantee protection through out a heat call.

I have a WM Cgm 7 that's been drinking 95* return water from my radiant for 21 years simple boiler bypass installed.. Reasons of survival rate can be attributed to a generously oversized boiler. But as far as condensing its a non issue as boiler is always above 135 after heat call.

Incidentally I have been hoping this thing would die so I can mod/con it. I hate pulling a perfectly good unit out to install a new one. That's why I have not worried about the return temp for the last 13 years I have had possession of the castle. Alias it lives on.


@ March 3, 2014 6:08 AM in Got my Sorbox today.

Be sure, and let us know how much debris gets pulled out of the system upon your first inspection after installation.

Is this an old existing system, or brand new?

Happy to help Roger.

Parallel or series

@ March 2, 2014 10:40 PM in Unequal circulators in series

When pumps are plumbed in parallel their flow rates will be additive with both pumps at the same head.

When pumps are plumbed in series their head will be additive when both pumps have same flow rate.

What do you need to do? Increase flow rate, or overcome more head.

Or just make it simple and get the right size pump.

Some things to consider

@ March 2, 2014 10:18 PM in Mixing Radiant Floor and Rads

One is out door reset for the boiler. You probably don't need 180* water to the radiators everyday of the heating season. IF your rads are oversized you may not even need 180 on the coldest days.

Your radiant will need a mixing valve it's done that way all the time. Taco I series comes to mind.

It would not hurt to do a room by room heat loss calculation. See if your rads can match the calculated loads with lower water temps.


@ March 2, 2014 12:46 PM in Got my Sorbox today.

1 cubic meter per hour = 4.4 gpm

.1 kpa = .03 feet of head

Or .1 kpa = .01 psi

6 bar is 87 psi

3 m cubed per hour is 13.21 gpm

Very low pressure drop

@ March 2, 2014 10:25 AM in Got my Sorbox today.

.9 kpa converts to .30 feet of head.
1 cubic meter per hour converts to 4.4 gpm
So at 20.25 gpm it's only .30 feet of head.

I thought it would be its design is like an air removal chamber.

Someone check my math though.

Pressure drop.

@ March 1, 2014 11:03 AM in Got my Sorbox today.

What is it. Nice product.

Up heaving of bottom cord

@ February 28, 2014 4:36 PM in Has anyone ever heard of this?

Would be due to the lateral bracing that transfers the load from top to bottom chord shrinking from temperatures in the attic being cold.

In other words the width of the top chord shrinks along with the length of the lateral bracing. As you get to the middle of the bottom chord span the lateral bracing is longer so more shrinkage, the higher the roof pitch and longer the span the worse it gets. Couple all that with dry winter air sucking moisture out of the lumber.

There is a different physics with what is POSSIBLY going on in the I joist situation.

Mark is doing exactly what I think the APA is looking for, and that is guidlines to protect their products. Except Mark will do it in a more direct type of verbiage not an umbrella statement of bits, and pieces of information put together into what THEY think it should be.

Hopefully his words do not get garbled in translation to a I JOIST guideline documentation.

I joist and floor truss

@ February 28, 2014 4:27 PM in Has anyone ever heard of this?

Are two different types of framing members. The method of transferring the load top to bottom chord along its length is the same principle though.


@ February 27, 2014 10:32 AM in Has anyone ever heard of this?

Ice they know what to look for as far as framing details not being followed. I would think that would be the first area to look for a problem. If those details meet their requirements then they will look at other possible sources of cause, and effect.

Bundy weld tubing

@ February 27, 2014 6:32 AM in radiant in ceiling?


@ February 27, 2014 6:03 AM in Has anyone ever heard of this?

I don't believe it is that extreme of a case. That would call for removal of the joist.

Been thinking about this open mindedly

@ February 26, 2014 6:05 PM in Has anyone ever heard of this?

When considering the letter to the RPA they are looking for help, and guidance. That's better than condemning radiant heat around their products.

The how's, and whys this happend or is happening is leading to a high temp plate less radiant system that is attached to the upper flange of the joist possibly not insulated.
In other words poor installation practices. If at the very least this is indeed a problem then maybe they could insert a section on radiant heating protocol in their instructions.

Now IF this is indeed an effect of high temp poorly installed radiant heating then this should be a temporary effect. If drying of the upper say 1/4-1/3 of the I Joist is causing shrinkage due to moisture being driven out of the wood then after the heating season the total I Joist detail should acclimate itself through out its cross section. Woods a sponge always seeking equilibrium. So deflection should dissipate during the non heating season..

I would personally like to see moisture meter reading through out the cross sectional area of the joist. Was this done? Or we're visual assumptions made we see radiant there is the source of the problem.

I would also like to observe loading of the span, and attachments to, and with in the joist. I'm sure the APA observed these first before looking else where for a culprit.

At the very least out of this I see an opportunity for the RPA getting a foot hold on proactive information rather than reactive information inserted into documentation for various wood product manufacturers. It always seems here that people come with problems after it's a done deal, and money is the only solution in righting a hacks wrongs. It gives radiant heating an undeserved black eye.

We can not only depend on people with problems finding heating

From the oriented strand (TJI) people

@ February 26, 2014 6:17 AM in Has anyone ever heard of this?

Not really what is going on with the APA issue, but does determine what moisture content is deemed serviceable.


@ February 25, 2014 9:08 PM in Has anyone ever heard of this?

I'm willing to bet that these are clear spans with no bearing walls or beams. This is typically one of the advantages to the I Joist system. Lighter materials spanning longer distances, with the ability to actually cut bigger holes for mechanicals in the middle 1/3 of the span verses the outter 1/4 in typical wood joists. Complete with knock outs for piping that seldom seek use because the framer is sloppy in lining joists up.

I agree with Bob

@ February 25, 2014 8:59 PM in Has anyone ever heard of this?

Apparently this is not an isolated problem the way the approach is taken from the letter. From your initial post this is what I thought to be an isolated case.

What Bob is saying about the radiant heating details is what I was leading to in my first post.

IF the APA truly is seeking help or advice then some details in the cases of radiant heating need be addressed. A poor install verse a quality one are two different animals.


@ February 25, 2014 8:07 PM in Has anyone ever heard of this?

Sounds plausible in theory Mark....Or are they picking and choosing some RPA guidelines to their own defense?

Obviously moisture content can be the culprit, but what is the standard acclimation period for their product? What percent moisture content is it shipped at, what operating steady state is it designed for, or most ideal?

The depth of the IJoist plays into this also obviously the taller the more potential for moisture content stratification through out the depth of the I Joist.

But then this can happen in a whole bunch of different scenarios.

Some how there has to be a middle ground between wood product manufacturers, and radiant heating. Surely some type of standard can be agreed upon verses the. Blaming radiant heating every time something happens, and radiant happens to be in place.

As you say how many roofs are framed with I joists, and what temperatures do they see through out its depth? But then no one looks at the roof for 1/2 inch deflection.

Staple up detail

@ February 25, 2014 6:40 PM in Has anyone ever heard of this?

If it were insulated properly the moisture content if it were elevated would not be able to escape rapidly. The only place for it to go would be in the sub floor plywood, and insulation.


@ February 25, 2014 6:13 PM in Has anyone ever heard of this?

I joist system? TJI is oriented strand board,, andBCI is ply wood.

Are the flanges LVL, or wood? LVL is laminated wood! wood flange is dimensional lumber.

Is he saying that the span deflected 1/2" in the center of the span? That's how I'm reading your post.

I think there are a lot of variables to look into on such a claim.

Span length?

I Joist height?

What's running with in the I Joist through knock outs as far as mechanicals plumbing etc. ( span loading).

Moisture content of material on site ( material storage until used)

Conditions in the basement ( humidity) if this is a floor over a basement.

How was the staple up detail ? Tubing next to the top flange of I joist?

Insulation detail of staple up?

I really find this to be a stretch in a moisture stratification with in the I Joist itself. I find it hard to believe that moisture would be extracted that rapidly from just the upper portion of the I Joist wood likes to equalize.... It's Mother Nature you know.

All in all I think there is product failure, and someone is looking else where for something to blame it on.

I was never a big fan of the I Joist products just no meat, and potatoes to them. Around here the fire fighters all most refuse to go in an involved house if they know the floor is supported with I Joists.

In the end to answer your question directly no never heard of it. Unless the floor was loaded with a flooring choice that the the joists could not carry. Stone etc.

I think a moisture meter wood be the tool of choice. I would love to see the readings top flange to bottom flange.

Non barrier loops

@ February 23, 2014 11:14 AM in manifolds in series?

Any way to separate the 3 non barrier loops, and run off a flat plate heat exchanger, and separate manifold? Be nice to keep the I floor in the cellar.

Just turn the power off Bob

@ February 22, 2014 12:50 PM in how prevalent is this?

To see how bright the new generation can be. I love that Twain quote!
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