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Joined on November 26, 2011

Last Post on September 14, 2014

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existing furnace

@ April 13, 2013 6:27 PM in Using a tankless for comfort radiant heat

would likely become the secondary heat source if I were doing this.  You need to begin at the beginning, which is a heat loss calculation for the house.

Tankless water heaters are not heating boilers.  They are designed to heat cold water to a fixed high temperature on an intermittent basis.  Their efficiency plummets when the inlet water temperature increases and they do not vary their output temperature based on load.

Hydronic boilers heat less warm water to more warm water on a 24 x 7 basis, and adjust their output water temperature to suit the outdoor air temperature.  While it is possible to make a tankless provide the heat for this task, the additional cost of a heat exchanger, buffer tank, outdoor reset control, and motorized mixing valve will easily negate whatever first costs you saved over buying a proper boiler.

putting out more heat

@ April 13, 2013 1:37 PM in BumbleBee question

would have to mean that the water is cooler at the end of the emitter.  Period.

Where else would the heat come from?

discontinued some years back

@ April 13, 2013 12:50 PM in Let's Try Again-TT Mini Smart

along with the SMART 20, unfortunately.

urban explorers

@ April 13, 2013 12:42 PM in Steam Traps, 1905

Anyone here from Detroit?  It's quite a target-rich environment...

depending on the outlet spacing

@ April 13, 2013 12:40 PM in Drop Header:Which way to Go?

you might be able to locate the header between the boiler risers.  Don't forget unions on the risers so you can pull a boiler if something comes up later.

Boiler logic

@ April 12, 2013 9:58 PM in BumbleBee question

Is actually pretty simple.  The modulating burner is driven to maintain supply setpoint (whether fixed or ODR controlled) via a PI or PID loop.  Boiler return temp is a product of emitter capacity and volume of water pumped.  The rise varies as the boiler modulates up and down maintaining that setpoint.

We can add sensors and controls (or buy those packaged as a ∆T pump) to improve this but we'll never know as much as the boiler does (plus the cost can really add up, particularly on smaller jobs.)

Lochinvar Solution

@ April 11, 2013 12:23 PM in Return temperature too low

How much damage is there to the HX and venting?

Is the outdoor temp sensor installed?


@ April 11, 2013 11:38 AM in Too many options - need help

They were accounting for total energy use, including electrical use by fans, controls, and freeze protection.  The deal killer is the NG cost, which would roughly double the payback around here.


@ April 11, 2013 11:26 AM in Indirect installation on Alpine with MCBA control

I'm not familiar with Burnham's implementation, but there may be a software setting which allows the pump to run on either call.

A wee bit

@ April 11, 2013 12:12 AM in Too many options - need help

on the mind-numbing side, but very well done.

Skip to p.60 and jump to p.83 if that starts to bore you.

They used $1.20 per Therm for NG and $0.12 per kWH for electricity and found:

The simple payback calculation showed that at current installed costs and energy prices 20 to 40 years would be necessary for a TWH to pay for itself, as shown in Table 23. The economics would be improved for TWHs on a life cycle basis if, as some TWH manufacturer’s claim the lifetime of a TWH is significantly longer than the StWH.

Here in NM, our electricity runs just a tad over $0.12 per kWH, but our NG is under $0.60 per Therm.  Tough math.

8-point sockets

@ April 10, 2013 12:19 AM in Skim port

Craftsman still makes them, but I haven't seen larger sizes.|4%22-Drive-Impact-Sockets---8-Point/ looks promising.

Is there a 'cooling' mode?

@ April 10, 2013 12:12 AM in BumbleBee question

That ought to invert the feedback loop.

Just to be fair

@ April 9, 2013 7:34 PM in Slab overpour "Radiant Green" hydronic heating panels?

Their new construction panel is listed as being 2" thick, while the remodel panel is listed at 1" thick.

hydrostatic vent testing

@ April 8, 2013 11:21 PM in Colorado Monoxide Case Moves Toward Trial

"perhaps a
hydrostatic test could be developed to prove the patency of joints or
leak test it. on site as installed. Maybe we'll end up using test balls
like plumbers do for DWV systems."

Makes perfect sense to me.

high temp limiters

@ April 8, 2013 11:12 PM in Control options with Vitodens 200 WB2B (Vitotronic 200 + Vitotrol 300)

Work just fine, but occupants need to be educated (and usually reminded) of their function.  Leave them ~2-4ºF above the indoor design temp and then carefully tune the curve.  Mind the deadband on the stats -- it can really mess you up.

If I were designing the onboard controls

@ April 6, 2013 4:13 PM in Pumping Awa Question

I would include not only a 0-10V output (a la Lochinvar), but also a TRIAC output (similar to Heat-Timer, Caleffi, etc.) to directly drive a wet-rotor circ.  This would allow the use of off-the shelf pumps with minimal installer training.

boiler pumps

@ April 6, 2013 4:01 PM in Pumping Awa Question

"Boiler pumps should be controlled by the boilers control via variable speed."

Amen to that.

∆T control is great, but it makes so much more sense for the onboard controls to manage the pump directly.  I really don't understand why this is the exception and not the norm...

You may not like this answer

@ April 5, 2013 5:15 PM in Ground water temp for On-demand hotwater in Alaska

but the simplest and least expensive way to solve your problem is to add storage to the system.  An electric tank-type water heater will be cheap and effective.  If you install it in conditioned space, the little bit of energy it loses will just act as a tiny supplement to your space heat.

good stuff

@ April 4, 2013 11:09 PM in Ground water temp for On-demand hotwater in Alaska

rule #1 for winter heating:  Don't throw away heat you've already paid for.

also check out

@ April 4, 2013 11:01 PM in spacing

some of the Webstone Hydro-Core stuff

proportional controls

@ April 4, 2013 10:42 PM in Pumping Awa Question

have been around forever.   Mechanical, pneumatic, analog electronic, and more.

Just seems a shame to be controlling all these newfangled modulating furnaces and boilers with on/off thermostats.  Look at all the intelligence and innovation we're seeing in networked tstats -- that communicate with the system over a one-bit, one-quarter baud channel.


@ April 4, 2013 10:26 PM in Pumping Awa Question

= Outdoor Reset Control
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