Security Seal Facebook Twitter GooglePlus Pinterest Newsletter Sign-up
The Wall


Joined on September 30, 2012

Last Post on June 26, 2014

Contact User

Recent Posts

1 2 3 4 5 ... 22 »

very useful information

@ June 26, 2014 1:12 PM in Initial target Flow Rate calculations

However, H.R.'s connection scheme isn't discussed, just top left to bottom right and bottom left to bottom right. Also, figures 15 and 16 reveal an impact on surface temperatures due to these flow distributions.

rad average tempreture

@ June 25, 2014 1:18 PM in Initial target Flow Rate calculations

Are the rads really going to have a 170 degree average?  The supplies and returns are adjacent, how do the rads channel water through the sections?  Are you converting from steam?

what kind of layout

@ May 26, 2014 2:04 AM in Home Run vs. "Stacked" Home Run for 3 Storey Home

What was the previous piping configuration like? None of of this is all or nothing. You could have copper in the basement with a transition to pex snaking up through the floors. You could have multiple manifolds distributed around the basement. In general though, take advantage the inherent qualities of radiators. This type of system can frequently operate at a high delta t which requires low flow. And low flow favors smaller piping.

electric rates

@ May 22, 2014 1:40 PM in Time to pull the trigger

How does electric compare to LP on a btu to btu basis there? There was a poster on this forum that had significantly cheaper dual fuel electric rates vs LP.


@ May 22, 2014 12:35 PM in Home Run vs. "Stacked" Home Run for 3 Storey Home

To answer your question, no i've never done anything that involved multiple remote manifolds.

In a typical home run system, the pressure drop across each heating element loop is equal. If you chop up the manifold and put part of it in different locations, the delta p drop will vary between the manifold sets. The piping out to the remote locations makes up the difference.


@ May 21, 2014 1:12 PM in Home Run vs. "Stacked" Home Run for 3 Storey Home

I think ideally, it's still about the same number of connections? (12 versus 10)

But if one is using pex and varying the pipe size, the inventory list becomes quite complex. And the larger diameters toward the ends are more likely to require elbows at bends. The connections tend to be in awkward places that frustrate the inexperienced, etc... lots of reasons someone might prefer a manifold in a given situation. Not that I'm advocating one way or the other. I feel like in a retrofit one would want to do whatever method works with the least destruction. In that context, the cost of the manifolds might not be significant, or may end up lowering the cost of the project.

no direct control

@ May 20, 2014 1:52 PM in Time to pull the trigger

There isn't a tight control on the water temperature. It's constantly rising or falling around the set point. The swing in temps is kept within reason by a differential value. A small modulating boiler can make good use of a tight differential, keeping a more even output to the floor. A bigger fixed fire boiler would make better use of a larger differential to prevent excessive cycling.


@ May 20, 2014 12:41 PM in Time to pull the trigger

Thermostat calls for heat. --> Boiler fires, heating water to the set point which may be adjusted according to the outside temperature if an ODR is used.

A modulating boiler would throttle back as it approaches the set point. There is no link between the thermostat and the set point. The set point is something you would program as part of the installation and probably adjust later if required.

Is there insulation under the slab? --something other than bubble foil like product?

I would expect

@ May 20, 2014 12:34 PM in Home Run vs. "Stacked" Home Run for 3 Storey Home

one to downsize tubing and manifold diameters if possible.

So maybe one could use something like a wirsbo junior manifold.

And of course smaller pex is easier to work with.

Generally, distributing the manifolds avoids having huge unmanageable bundles of pex coming together at one spot blowing out all the studs. Even 3 rads requires 6 runs of fairly large outside diameter tubing. (The stated diameter is for the inside --1/2 inch is more like 3/4 inch, requiring an even bigger hole.)

But if you're using the existing rads in place, perhaps it's best to using the piping layout that was originally employed?


@ May 17, 2014 12:13 AM in Time to pull the trigger


What does the house need?

@ May 14, 2014 12:38 AM in Too big of a Buderus?

Maybe all the options are too big.  Has someone done a heat loss calculation?

small load systems with CI boilers

@ May 4, 2014 2:48 PM in List of small mod/cons

Can any of those tank in tank water heaters be used for both hydraulic separation and load buffering?  The primary fluid storage is often quite a bit.  The brochure for TT's multi energy series, for example, seems to illustrate several examples where the tank is acting as the hub for the system.  But that tank comes with an extra coil for solar, etc, it's not a basic model. 

1700's basement

@ April 30, 2014 12:16 AM in Can Air Source Heat Pump Sit under the house?

Tell us about your project.  The house originally dates back to the 1700's?  At some point steam was installed?

not possible, floor is not working

@ March 29, 2014 12:59 AM in Infloor Radiant Heat issue

55 kilowatt hours for a month is roughly equivalent to the output of a 75 watt bulb.  At an average temperature of 11 degrees F, it's clear the floor is not working.  Did your guests turn up the thermostat for the rinnia?

Do you have enough propane to run the system for over a month?

What is the radio control unit that you spoke of?

zone hand-off

@ March 22, 2014 12:40 AM in Please critique this design

Zone hand-off is the opposite of what all these sync systems are trying to accomplish.  The goal is to prevent dispersed calls for heat and always fire into as much of the radiation as possible.

A hand-off strategy could only make sense if the mod/con was forced to operate at a fixed setpoint.  In this case, even though the burner can modulate, the emitters can not, creating a mismatch between the house's true demand and the systems output.

In a nutshell, it's better to fire 10k total into all the radiation all the time, as opposed to firing 10k into one zone at a time.  The latter requires higher setpoints, increases temperature swings in the zone, and reduces the connected load to the boiler which increases the cycle frequency.

zone sync

@ March 21, 2014 1:21 AM in Please critique this design

The Tekmar system syncs the zones at the beginning of the cycle. The thermostats also provide indoor feedback to an ODR module, which adjusts the setpoint to match the loads at the minimum supply temp, and automatically adjusts the differential if required.

The Honeywell system is probably very similar but I have not read up on it as much.

As far as I know, there is no zone sync method that uses a hand off strategy, though. That wouldn't make sense if the system is in control of the supply temps and is allowed to adjust them to optimally match the emitters.

It would be interesting to see someone install an indoor feedback system, they seem pretty rare.


@ March 20, 2014 12:53 AM in Pex

What is the pert stuff like to work with? What's the advantage?

delta control apparently only goes to 25

@ March 19, 2014 1:46 AM in Please critique this design

A forum member named smihaila asked Lochinvar detailed questions about some of the more advanced pump control features on the boiler you are considering.

From a post titled: Some answers from my Canadian Lochinvar rep

Q3: What fine-tune parameters are available in the "Smart Control" logic
for the customization of the "Const Delta-T" operation which seems to
be supported via "0-10V BLR PMP OUT"?

A3: The Knight Smart System controller will always try to maintain a 20F Delta T (Default) but has a range from 15 – 25 using the PC Software.

boiler pump

@ March 18, 2014 1:42 AM in Please critique this design

The boiler pump would be configured to always run with the system pump somehow?


@ March 18, 2014 12:36 AM in system advice

hePex, even with its o2 barrier is not truly oxygen tight. PAP is 100% tight. PAP also moves less than regular pex due to its stiffness and substantially less coefficient of thermal expansion. Less movement generally translates to less noise, and perhaps less wear and tear if the tubing is rubbing on something sharp.

The max temperatures aren't really important here, even with a radiator system.

too good to be true

@ March 18, 2014 12:21 AM in system advice

Either they removed those kits or I am going crazy and my memory is failing me. I can't find it anywhere on that site. I recall there being manifolds with adapters included for specific pex sizes/types, but maybe it was all a dream.

sorry to get your hopes up, fixerDIYupper :(


@ March 17, 2014 12:12 AM in system advice

You can buy Uponor manifolds that come with matching QS fittings at basically no additional cost. Why do you need 80 of them?
1 2 3 4 5 ... 22 »