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Joined on November 26, 2011

Last Post on July 30, 2014

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begin at the beginning

@ March 25, 2013 2:43 PM in Replacing a BW Combi Core unit

The first step is a heat loss calculation on your house.

A modulating condensing boiler will also vent with PVC, will outlast several tank type heaters, and burn less gas.

old requirement before options

@ March 25, 2013 10:53 AM in Oil boiler to gas boiler conversion

did anyone do a heat loss calculation?


@ March 25, 2013 10:34 AM in Buderus GB125BE/30


found ratings on p.4 of the G125 datasheet

/30 = 30 kW = 102 MBH gross output.

Taco iSeries-R

@ March 25, 2013 10:27 AM in Suggested Radiant Mixing Control

is the simplest and least expensive option I know  Control over ORC parameters is limited, but they get the job done.

did not realize the 4" was still intact

@ March 24, 2013 11:36 PM in Water service freezing

frozen and burst are two different beasts.  Spent nine days this January without water thanks to a shallowly buried main on the north side of the house we are in.  Fortunately it was galvanized so once it thawed out, all was well.  Frost depth here averages about 10" and code requires 18", but some people never learn...

Did not see an IOM for this

@ March 24, 2013 8:15 PM in Buderus GB125BE/30

and noticed that Buderus has it on their "Previous and Discontinued Models" page.  Any idea why they dropped what I believe was the only domestically available residential condensing oil boiler?  With our current (and probable future) oil prices...


@ March 24, 2013 1:13 PM in Adding a secondary pump to my radiant heating system

Is the ODR-controlled Taco mixing valve I linked to above

The Bumble Bee is a variable-speed ECM (electronically commutated motor) ∆T circulator from Taco.  Its highest curve is roughly equivalent to a 008, but it will constantly adjust to maintain the set ∆T.

PEX head

@ March 24, 2013 12:50 PM in Adding a secondary pump to my radiant heating system

I'm sure my Rad Pad is here someplace...

I get 3.79 ft/100' (at 180F) or 4.06 ft/100' (at 120F) from the Uponor CDAM for 3/8" PEX at 0.6 GPM (2 ft/sec.)  This would imply somewhere between 7.2 and 7.7 ft depending on temperature for the loop.

I'd start with an iSeries-R and see how things improved.  Perhaps a Bumble Bee for the radiant loops later depending on what resulted.

cap a piece of 2" PEX?

@ March 24, 2013 12:15 AM in Water service freezing

Not quite sure what you are describing (thanks.)

Confused by the PDF above

@ March 23, 2013 10:50 PM in Adding a secondary pump to my radiant heating system

titled "Radiant Sketch" which shows a supply manifold with ports marked
140 140 180 190 170 170
and a return manifold with ports marked
 .7    .7    .6    .6    .7    .7

I figured the numbers on the supply ports were temperatures, but can't imagine how those could result from the piping diagram shown (unless they represent cheap clip-on thermometers which have not been calibrated.)

supply temps

@ March 23, 2013 7:32 PM in Adding a secondary pump to my radiant heating system

Are showing 170-190F on radiant loops?  If those are accurate, I'm wondering what the mixing valve is mixing down from...

Those big delta-T numbers you're seeing are a result of hot water hitting a cold floor.  Outdoor reset with constant circulation will stabilize those at a level perhaps a bit better than the 30F you are seeing after an hour of operation.

The way your system is currently configured and controlled is kind of like driving a car that has no accelerator or brakes -- your speed can only be controlled by depressing or releasing the clutch.  Imagine driving that car on varying terrain -- while only being able to see about 3 feet in front of your bumper.  That's roughly what an indoor thermostat controlling a fixed speed circulator or a zone valve can do.

Outdoor reset gives you an accelerator and brakes while increasing visibility to something like 200 yards.

the next stage

@ March 23, 2013 3:16 PM in Off-Season Savings?

The T-KJr2 is pretty affordable.

Given the summer-only occupancy, you might even look at batch solar.

outdoor reset

@ March 23, 2013 2:51 PM in Adding a secondary pump to my radiant heating system

changes the temperature of your heating water based on the outdoor air temperature.  As the outdoor temp warms up, lower temperature water is supplied to the emitters. explains pretty well.  While it's useful on almost any type of system, it's pretty much a requirement for maintaining a stable room temperature using in-floor radiant heat.  Given that you have a conventional boiler and a mixing valve, fluid temp for your floor loops could be controlled by replacing your existing mixing valve with something like

I should have asked if you are measuring those large ∆T numbers when the system starts up and if they drop later as the system comes up to temperature?  If so, adding ODR might be a better move than installing a larger pump.

You could also add outdoor reset to your boiler, which would vary the temperature in your main loop depending on weather, probably saving ~15% on your annual fuel bill.  The mixing valve controlling the floor loops would not be affected by this, but overall system comfort would increase.

bubble wrap

@ March 23, 2013 2:15 PM in Adding a secondary pump to my radiant heating system

is not a particularly effective insulating material.  How are your basement temps?

I would seriously consider an outdoor reset-driven mixing valve for those floor loops.

radiators and thermostats on the first floor

@ March 23, 2013 1:56 PM in Adding a secondary pump to my radiant heating system

So the radiators on the first floor are fed by a different pump?

Is the tubing embedded in concrete, or is this a dry floor system?  If the former, you really can not rely on a conventional thermostat to regulate space temperature.   Outdoor reset control would be best, but a hydronic thermostat with a slab sensor would represent a major improvement.

so all this serves is the floor loops?

@ March 23, 2013 1:40 PM in Adding a secondary pump to my radiant heating system

and there are no zone valves downstream of the pump?

What is a flat curve?

@ March 23, 2013 12:45 PM in Adding a secondary pump to my radiant heating system

When we refer to a circulator as having a flat curve, we are describing a pump which does not dramatically increase its head pressure as flow decreases.

Take a look at and you will see why the 007 and 0010 are said to have flat curves. and explain why this characteristic is desirable for many heating applications.  High head pumps have their place, but they are not "flat curve" designs.

Tankless water heaters HAVE been out there awhile

@ March 23, 2013 11:53 AM in propane wall mount boiler

Paloma, Takagi, and Rinnai have all been selling gas-fired tankless water heaters for roughly 40 years.  The Europeans figured out electric tankless decades ago.

At least with regard to the better brands, installer and user misunderstandings cause far more grief than poor design does.

Sprinter engines

@ March 22, 2013 9:26 PM in Sprinter look a like from Fiat

Just about every I5 owner I know is very happy.  Can't say the same of the V6 owners.

12 inches

@ March 22, 2013 9:19 PM in finned tube convectors with modcon

above the valve, assuming the emitter is not directly underneath, would likely represent a major improvement.

sensor lying in the enclosure

@ March 22, 2013 4:13 PM in finned tube convectors with modcon

Belongs the short list of truly cockamamie ideas.  That's worse than having a standard TRV sticking out the side of the enclosure.  How far above the enclosure (but not above an element) could they be relocated?

thought it was already insulated?

@ March 22, 2013 12:18 PM in Water service freezing

If the replacement bundle is smaller than the ID of the 4", you should be able to winch them in without having to burst the old pipe.  A 2" along with either a pair of 1/2" snowmelt pipes or some heat trace tape should be easy (barring inconvenient elbows.)  2" PEX with a heat trace and some insulation might be another option. 
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