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scott markle

scott markle

Joined on March 28, 2007

Last Post on February 25, 2014

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nice looking

@ May 24, 2011 11:33 PM in triangle tube challenger

Nice work . I like the use of webstone P/S T pump flange combo. What's up with the monster pump on the primary, do they spec this? I don't like small boilers that demand that kind of head just to push the required flow through the HX.

So many new boilers out these days it's hards to know what's best, on the combi front I like the idea of units that include a pump and expansion tank, anybody see the new Rinnai boilers?

head conversion

@ May 24, 2011 11:17 PM in Gravity system

So head times 2.31 equals psi and psi times .434 equals head.

Any compelling reason to keep an open system open?

ultra fin

@ May 24, 2011 12:18 PM in Insulating Radiant Under Wood

For joist bay heating (high temp radiant) this is the type of plate to consider.

From what I remember It's recommended that this product is used with pex/Al/pex, because it's stiff and doesn't move so much with expansion, but if you do a good job with hangers I think you could make it work with regular pex, just confirm with the manufacturer that the pex your using (if it's not pexALpex ) will make good contact with the plates.

R-19 would probably do the trick, but as Chris points out how much goes up and how much goes down depends on the R-value of the floor as much as what's bellow it, maybe a bit less so in a high temp joist bay heating arrangement where the dynamic of rising hot air comes into play. I'm sure ulta fin has some guidelines that you could use for determining appropriate levels of insulation

head pressure

@ May 24, 2011 11:52 AM in Gravity system

If I understand head pressure correctly you will need 30ft of elevation from the boiler to the top of your open system to achieve 12.9 psi at the boiler. 30X.434=12.9

From my experience testing drain lines by filling them with water I would have thought this would be less, somebody let me know if my understanding of static head is flawed.

With this in mind be aware that some boilers a not very tolerant of lower operating pressures. The sensors "trip" and cause a shutdown. The budarus GB142 comes to mind at requiring more than 12-13 psi to operate. I also believe that TT recommends a few psi above this standard pressure to ensure there are no nuisance shutdowns. Viesmmans are more tolerant, my own boiler which is on the second floor of my house operates at 10 and I'v seen it go to around 6-7 before shutting down. Looks like the new Vito's are using a flow switch as opposed to a pressure sensor so this might be a reason to look at these boilers if your attached to the idea of keeping things in the 19'th century.

Why not loose the old expansion tank and put in a pressure relief valve and diaphragm tank? It's remarkable that an open system like this can last as long as it has without rusting out. Since this is and open system and there is likely to be lots of rust floating around I'd recomend a good flush with Romar or Fernox and filling with a inhibitor, Also consider a dirt separator, spirotherm makes a very nice combo air dirt and hydraulic separation device, although I suspect the system will take so little energy to pump that you could pipe it direct (no primary secondary).

Also keep in mind that gravity systems when converted to forced circulation can become imbalanced, TRV's are a great way to deal with this. The old vito's also incorporated pump logic that would slow circulation when loads were down, I don't know of a way to do ODR pump regulation but I notice that there are coding addresses for it on the new vitos even though the built-in pump that could do this is no longer part of the package.


@ May 22, 2011 11:28 AM in aq251 reset

The boiler return sensor is optional, it's used to protect the boiler from low return temps.
the supply sensor should be measuring the temperature out of the boiler, make sure it's placed upstream of the DHW T so that it can measure supply during DHW production.
This control is designed to work with special communicating thermostats. they do more than just display the outside temperature, they "communicate" with the reset control about the actual room temperature if it's rising or dropping, and how far from target it is, this information is used to determine what the supply temperature should be (Indoor Tweek of the ODR). and to sync the run cycles of the installed stats as best possible.

Sound like you should spend some more time with the supporting literature, getting the sensors in the right places is crucial, but you also need to commission this thing and the default settings may not cut it.

zone sync without boiler control

@ May 17, 2011 1:52 PM in Zone Load Synchronizing - Is it worth it?


Can you wire a Tekmar zone manager without a boiler control (420 or whatever)? How does the zone manager get it's power?

While the backside wiring on the newer tn2 house controls and need for an external transformer is a bit less tidy, I appreciate the lower cost of this this line and the two wire thing is huge for retrofit.


@ May 17, 2011 1:33 PM in glycol feeder and mold

It's before the fill valve, I stated it wrong the first time, thanks for catching that.

I'm really not not sure what the pre charge should be. The one pictured is just at the factory preset of 12 and it works fine. I guess I'm a little nervous that this could be putting to much strain on the rubber by stretching it further than it should, so in the future I'll probably bump up the pre-charge. I'm a little less inclined to mess with a pre-charge since I'v learned that it's pressurized with nitrogen and I don't have a nitrogen tank.

I included a pressure gauge to monitor the glycol charge and a boiler drain for initially purging air from the top of the tank and pipes leading to the fill valve. This system is actually just charged with water, but I like the idea that there is a finite amount of make up water especially on a radiant system with so much pipe and the increased chances of a leek. This actually was put to the test twice when the insulation contractor and then the flooring guys punctured the tubes, it was a mess but considerably less fluid was spilled than would have been if the system was tied to the domestic lines. It's been running for two years now with no noticeable drop in pressure. The configuration of the boiler fill valves makes it possible to boost the charge without introducing air into the system (if it is ever necessary). The main reason I did it this way was because it was new construction and there was no water in the domestic lines, mid winter construction project.

I vote yes

@ May 17, 2011 12:25 PM in Zone Load Synchronizing - Is it worth it?

I think you are overstating the price difference a bit, between conventional stats and zone relay VS. a synchronizing control such as the tekmar TN2. If you want this much zoning your already committing a lot of resources to thermostat wiring, zone valves, isolation, etc. Were not supposed to discuss pricing but i think if you subtract the cost of all the conventional stats and relays this upgrade is less than you state. Considering the significant cost and relitivly long payback periods of a Ground source geo/radient system I think it's silly not to include this.

Alternately I'd consider pairing down the number of zones even consider omitting indoor feedback altogether if the house is tight and doesn't have any crazy glass features this can work fine for a set it and forget it type. Balancing manifolds can help match areas of the house with different loads. Do you really need this much control, slabs are so sluggish anyway , they are not well suited to setback and will disappoint the user who wants to make frequent changes to a thermostat setting.

If you feel you must have so much zoning and don't want to use a synchronizing control consider leaving a perimeter loop of each individual zone"wild". IE don't kill all the loops in a zone when the stat is satisfied. Leaving a perimeter zone wild will help moderate the inertia issues and micro load cycling.

Also I believe that honywell makes a paired down AQ zone control that does synchronization without all the other stuff.


@ May 17, 2011 8:58 AM in glycol feeder and mold

Yes Mark you have presented this idea before. I am indebted to the wall for great ideas like this one.

As an early adopter of this technique, perhaps you can shed some light on the etymology of the term "pig".

My apologies for the missing attribution :)

Glycol Pig

@ May 16, 2011 4:57 PM in glycol feeder and mold

I think the open glycol feeder is a bad idea.

1- glycol will go bad in contact with air

2-glycol can feed bacteria and mold, especially if it's open to the air

How much make up water does a closed loop heating system need?

I favor a very thorough purge and a glycol pig- A dedicated expansion tank (with the bladder pressure jacked up) downstream of the fill valve that is pressurized 25-30 psi with the glycol solution.


@ May 16, 2011 4:39 PM in mixing brands of pipe with manifolds

If the pipe is SDR-9 and so is the manifold you should be fine. Don't use fittings with compression rings or sleeves that were not designed for those fittings. But if it's an SDR-9 fitting and SDR-9 pipe the brands don't have to be the same. (in my opinion)

ground as thermal mass

@ May 16, 2011 4:26 PM in Rigid foam slab insulation

The old Heatway design manual took a similar position on slab insulation. Although the manual was well written and had a lot of good information about radiant heating and control strategies, I wonder if this opinion was researched by the same people who did the rubber compounding for entran-2?

I would imagine it's fairly complicated to model the movement of heat through the ground, lot's of variables. Still I don't think you have to be a math head to understand that an enormous 55 degree heat sink in direct contact with a 72 deg slab is going absorb a significant amount of energy. Yes the earth will warm and a temperature gradient will form under the slab such that the rate of transfer to the earth will gradually decrease and stabilize but they will never reach equilibrium, energy will always be moving into the ground. How much energy is lost to different soil types and what is the point of diminishing return on insulation are interesting questions, I have a memory of an experiment that may have been posted here where temperature probes were placed at varying depths under differing insulation types to try and inform this question.

Also keep in mind that many soils have water moving through them, Imagine how much heat a slab could loose to the earth if (cold) water was moving through the soil directly below. Extruded Polystyrene is our friend, skimping on slab insulation is a false economy.


@ May 11, 2011 9:26 PM in PEX Installer Preferences

Viega's stainless rings and tools are excellent, and they periodically sell them at a promotional prices.

Occasionally it's difficult to get the tool into a tight space, the expansion system does allow for making connections in confined spots.

As far as temperature is concerned I kind of remember Viega stating a minimum recommended pressing temperature, colder than uponor, but not way below freezing if I remember correctly.

I have some concerns about the plastic uponor fittings becoming brittle over time, especially where they are exposed to high temperatures. I'v seen overheated (but probably not over 180) heat-link manifolds that were totally degraded and I could break apart with my hands.

Viega and vanguard

@ May 11, 2011 8:37 AM in Using Uponor Propex fittings on different pex ?

I would be wary of using an expansion fitting on a non-uponor pipe, but I'm quite comfortable using Viega press fittings on other brands of pex that use compression style fittings.

Viega kind of killed the whole pipe and fitting match argument when they bought Vanguard and said we could use the original press fittings too. What you don't want to do is use a viega press ring on just any type of fitting, the press ring uses a very shallow ridge on the fitting. Viega is now selling their fittings with the ring pre-attached and will phase out the separately sold rings to avoid this.

As far as insurance is concerned, even if you did everything by the book you would probably end up making a choice between filing a claim and loosing your insurance/skyrocketing rates, or just taking responsibility for the problem your self.

cemented in

@ May 3, 2011 3:57 PM in Help!

The fact that those vents were cemented in sounds like trouble, to remove. Could it also be a bad practice by not permitting expansion and contraction.

If you could use indoor air you could halve your vent length. If removing the cemented vents is impossible maybe some kind of controlled outside air supply for the boiler room is an option.

I was curious about the vitdens cpvc venting requirements but couldn't find the specs. As I recall the 100 could do 80ft of 2''. If the restaurant could use a wall vent instantaneous maybe 6 120k boilers could do the trick?


@ May 3, 2011 2:14 PM in Help!

Hope your able to influence this one in a positive direction.

flow direction

@ April 28, 2011 5:25 PM in heat transfer between storage tanks

The tank mixing pump, is sucking from the hot outlet of the boiler powered indirect, pushing to a mid-level tapping on the solar tank, and returning to the boiler indirect via the top of the solar tank to the "cold" inlet on the boiler indirect. Not a lot of hours clocked on this pump yet but I have seen the 80 gal boiler tank 15 degrees above it's set-point in march, so I'm glad it's part of the setup.

Home owner called yesterday, the controller was flashing a red alarm, it was an error related to the flow sensor, by the time I got there it had reset and everything was running fine. I did get a bit of air out of the bleeder, I like that the control has these alarm features just hope I don't get more nuisance warnings.

roughen the thread

@ April 27, 2011 7:03 PM in loctite sealing thread

learned something from the video, they want you to roughen the thread, I'v seen euro radiator valve nipples that had little cuts in the thread like this and wondered what it was about, anybody ever do this to male threads?

I do like the ability to reposition the joint by 45deg. without starting over.

loctite 55

@ April 27, 2011 6:53 PM in loctite sealing thread

I'v had no leaks using this stuff, it's now supplied with Viessmann indirects, they used to provide hemp. I found the hemp really hard to wind onto the threads, but this loctite thread has a bit of tack to it. Sometimes it feels like it's bunching up and I'll start over, it's clean to work with. There does seem to be a bit of technique to applying it I think I'll watch the video!

indoor outdoor

@ April 26, 2011 12:21 PM in oversizing mod/cons YES!!!!

Yes, the tn4 and tn2 stuff is uses communicating thermostats and combines indoor and outdoor feedback to determine supply temperature.
It also attempts to sync. the zones and helps with the micro zoning problem you mentioned.

One of the best part is that the stats have authority over the reset curve, so when the user turns down the stats they are in effect making a parallel shift of the curve. Same thing if they want to crank the heat. I think the new and less expensive two wire tn2 house controls work even better than the older tn4 stuff. It's really a great product. I'v never done a honywell aq2000 but it's very similar.

heat transfer between storage tanks

@ April 26, 2011 10:47 AM in heat transfer between storage tanks

I have a two tank system and have some concerns about heat bleeding back from the boiler heated indirect to the solar tank.

The arrangement incorporates a stainless circ to mix the two tanks (differential controlled) this pump line runs from the hot outlet of the boiler tank to a mid- level taping on the solar tank, it has a check valve.

The Hot outlet of the solar tank feeds the cold inlet (perforated dip tube) on the 80 gallon
smart indirect heated by the boiler, this line has no check valve.

I was by the other day after it had been cloudy for a while and the top of the solar tank was around 90 degrees, which seemed surprisingly hot, is it possible that heat is being bled through the single pipe connecting the tanks? should I have a check valve here as well?

This got me thinking that should the check valve stick open it could seriously impact the amount of solar energy collected, it's not easy to detect this sort of thing, and I can imagine a situation like this could go unnoticed for years. Guess thats another reason why energy metering is a good idea, it provides some baselines that would identify a problem like this.


@ April 26, 2011 10:28 AM in Pipe insulation for steamback systems

I'm a bit skeptical of all this steamback talk.

The only collector that I'm aware of that seems specifically designed to assist this effect is made by Shuco.

These residential flat plates have no internal header, just a single small diameter serpentine pipe, that gets connected in series to the other collectors (max of three I believe)

Seems to me that the combination of a very low volume of glycol in the collector and no larger diameter header is why these collectors are capable of self evacuating so well in stagnation conditions. I would be wary of assuming that just putting a large expansion tank on any collector will effectively protect the glycol from damage. Even where the collector hydraulics optimize this effect I don't think we want to be to casual about stagnation. My take is that steamback is a last resort failure mode.
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