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Joined on January 19, 2012

Last Post on April 19, 2014

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@ July 1, 2013 9:28 AM in asphalt laminated kraft paper and staple up radiant floor heat

If your design temps are truly 120, I think you should be ok. Has a proper heat loss been done? My concern is that if you end up needing  more like150 degree water you will start to get off gassing. Regardless of what onix advertises, I don't think the assembly you describe will produce more than 10-15 btu/ft. This seems like an unlikely heat loss for a 1930's NE home. Transfer platse make a huge difference in the reduction of water temps.


@ July 1, 2013 9:15 AM in condensation on floor

I hate to be the one to state the obvious. You need to dehumidify the air. The warm air in your basement is saturated. This may be due to the surrounding soils being moist and perhaps a lack of proper vapor barriers under the concrete. As soon as you cool the air, it can no longer hold on to vapor and it condenses. The moisture you see under the bed is inconvenient, I would be more concerned about the area you cannot see, like behind the drywall. These areas can turn into nasty mold farms.
One way or the other, you need humidification. Also be sure you have proper gutters and drainage around the house.

Further Thought

@ June 30, 2013 10:26 AM in Taco X-Pump block, larger HX availibility

A larger boiler circ would help close your 20 degree delta. This would be needed with a larger exchanger.
A larger system circ would tighten your system delta. This would not have a significant effect on overall absorption. The average temp would stay the same, the transfer would be more even.
A larger plate exchanger will close the gap between boiler side and system side temps. the boiler side delta t would increase and transfer would be limited unless boiler circ is changed.
I am still thinking you should change it all or go with what you have.

Entire assembly

@ June 30, 2013 9:40 AM in Taco X-Pump block, larger HX availibility

Right now you have a delta of 35 on the system side and approx 20 on the boiler side.
You would get a bit more transfer if you increased the flow to the system side. The slab is not absorbing much energy  from 85 degree return water. 30 btu/ft is really pretty good. If you really want to move the energy faster, you should upgrade both circs and the exchanger. Unless your boiler is cycling causing it to burn less efficiently, I don't see that you have a problem.
99.xx % of all 007 circulators are wired to run wide open. They are only occasionally used for injection.What is you concern with the system running at 100%?


@ June 30, 2013 9:08 AM in Taco X-Pump block, larger HX availibility

5 x .75 = 3.75 gpm. 3.75 x 500 x 35 = 65,625 BTU/hrs.
 I think your limiting factor is not the plate size, but the system side circulator.
I am assuming you are starting with a thick cold slab that is capable of absorbing BTU's quickly.
I have to agree with SWEI that this may not be the best strategy from an occupant comfort point of view.
Rich is also correct that unless you have circulators in series the boiler side of your taco is circulating 6 gpm or less.
You could increase the transfer of your system by boosting your system  side circulation. The possible side effects could include occupant discomfort and reduced boiler return temps leading to condensation.
The buffer tank is the correct solution. Siggy has written several articles on wood boilers


Little more info.

@ June 29, 2013 9:59 PM in Undersized boiler

What is the footage of the house? What type of construction? What part of the country? How many feet of baseboard?
Is this a new install or replacement boiler?
Pictures of the boiler piping is always useful.
A heat loss calculation is the definitive way to determine boiler size. There are many free online calculators. Check out Taco's flow pro university if you are looking for some free lessons.
If you post the above info someone can tell you if you are close. In many cases the distribution piping is incorrect.This will lead the knucklehead installer to turn up the temp. Higher temps will cost you efficiency.2

Why all the zones?

@ June 28, 2013 5:34 PM in Radiant heat

To answer the original question. It really depends on what type boiler and and how it is piped.
Unless I am missing something, it should all be on one zone. Unless the rooms are closed off to each other or have drastically different solar exposure or heat losses, they should be on the same zone. Separate zones will cost extra money and reduce overall efficiency due to short cycling.
The owner is always right, unless they are wrong. Then it is your job to explain it to them.


@ June 27, 2013 5:35 PM in Loop length?

I don't think you should be using 300' as your max. The head loss and associated reduction in flow goes up exponentially as you pass the 250' mark.  I would design for loops in the 200'-220' range and consider your max 250'. This will give you more even heat and allow you to use smaller circulators.
Balancing is also less important with shorter lengths. You will never notice a temp drop on a floor with 150' and 225' intermixed. A floor with 225' and 300' would be noticeable.
I would recommend going shorter, add a loop to get your average around 200' and don't sweat having some minor differences.



@ June 27, 2013 9:35 AM in Mark Franks

My point is that their is not a correct fact in the article. The heat pumps run on electricity which is produced in a fossil fuel burning power plant. As Henry points out the net efficiency and carbon footprint doesn't change. A 3 COP from a 30% efficient power source is no different than a 90% efficient boiler. A 3 COP running off PV panels is a different matter.

Mark Franks

@ June 27, 2013 7:37 AM in Mark Franks

As much as I love my Thursday new letter. this one is simply not true.

Henry Gifford does a great job explaining this one


Bad Quick connect

@ June 26, 2013 7:55 AM in Weber Natural Gas Grill Home Hookup

It sounds like there is something wrong with your quick connect. Maybe some debris got inside and plugged it up. It could also be an internal part was dislodged and is obstructing the flow. If it was a simple air valve, I would suggest trying to clean and repair it, since it is gas, you really should just have a new one installed. I would buy it as a set with both ends to be sure they are compatible. Don't worry about the 3/8" vs 1/2" thing. Weber  has already figured that out. If it worked before it will work again.

Warm Board

@ June 22, 2013 9:54 AM in Radiant - Gypcreet

I am guessing you have finished ceiling below. Can you blow in insulation?

First off  bubble wrap will not work in a radiant system. The "reflective" value only works in an air space. Even then it is suspect and not allowed by most codes. The other thing to look at is the compressive rating. If the product will compress under load, the gyp will crack. If you can afford the space rigid insulation would work.

Why are you looking for a high mass system? I would take a hard look at a product like warm board. You can put rigid insulation under it and eliminate the thermal "flywheel effect"



@ June 22, 2013 9:40 AM in Multiple ODRs?

Tough one,
I love the TT boilers. This is their biggest weakness.

 Tekmar has great stuff that will always run the boiler at the lowest temp, it will mix down your slab when needed. They are not cheap.

The thermostatic valve will give you a good max protection but will not give you ODR when both zones are calling.

A non thermostatic will allow one zone to lag the other and have a reset curve. You would have to always run the boiler at the the higher temp costing you some efficiency.

You could use an odr mixer and keep the boiler the way it is. This solution may take a little longer to get dialed in but would work well. It would be a bit "messy" from a style point of view but would be inexpensive and work well.


@ June 21, 2013 2:00 PM in Sloped ceiling insulation problem

That is a good read. I will throw it in the file. These things are so handy when you are trying to explain concepts to folks.Fine homebuilding also did a great one on ice dams.

It works

@ June 21, 2013 1:13 PM in Sloped ceiling insulation problem

What I described does work. A great deal of attention needs to be given to the details.


@ June 21, 2013 1:06 PM in Issue - Condensation?

Is your dryer vented to the outside?
Why are you draining your pipes?
Try putting a cheap humidistat down there.

Spray Foam

@ June 21, 2013 10:23 AM in Sloped ceiling insulation problem

My understanding of this is that if you fill the void without 100% air sealing and the correct r value, you create a condensation issue which leads to rotting ect.
If you use the correct amount of closed  cell foam insulation based on the relative humidity and design temp in your area you eliminate the condensation and have the best possible assembly.
It is kind of like, why does moisture form on some refrigerators and not others in varying climates?
I may stand corrected on some of this, but that is the general idea.



@ June 21, 2013 9:13 AM in High vs Low efficiency gas boiler?

I am truly happy that you love your boiler and have had no issues with it.

I am not sure why you take it so personally when the pros on this site discourage people from buying one due to it's overall poor track record. Do you think they are making it up? It is very expensive for a contractor when they install a lemon. Many of the navien units were lemons. This is not the contractors fault, however they lost money trying to warrantee a faulty product.

As for the 10 to 1 turndown ratio. Going from 5 to 1 to 10 to 1 is an easy thing to claim, it is a difficult thing to do. Anyone who has either researched the subject or used a combustion analyzer to verify these claims will tell you that navien is stretching the truth at best. The excess air goes to pot and the efficiency suffers. This is a fact. Standout companies like Triangle Tube will tell you that this is why they do not offer 10 to 1.

It is great that you have had success with your boiler. Your opinion is based on your experience with your boiler and the marketing hype from Navien. And yes it has saved money over your old system.

The people you claim "hate" combi's on this site, have a significantly different  skillset and level of experience.



@ June 20, 2013 5:46 PM in outdoor reset for radiant floor heat

It sounds like an unusual setup. Are either the boiler or the radiant loops tied into the domestic water or are they isolated?
It sounds like you need to vary the temp in the tanks based on the temperature outside (outdoor reset control).This will help you apply the correct amount of energy to the floor based on your actual heat loss a any particular time. There are quite a few ways of doing this. If you post a picture or drawing of your system we should be able to point you in the right direction.
Depending on how much solar gain you are experiencing, you may want to consider Tekmar TN4 controls. The TN4 system has the ability to anticipate an overshoot. They work pretty well. With a high mass slab it is very hard to completely eliminate overshoot.



@ June 20, 2013 4:41 PM in Which boiler

You should use the heatloss number to size the boiler.
The attached load will come into play if you use outdoor reset, particularly in a condensing gas boiler.
You are stuck with oil, yes?


@ June 20, 2013 3:31 PM in High vs Low efficiency gas boiler?

As usual the answer is "it depends". Although your baseboard heaters were designed for 180 degree water, they may not need anywhere near that much to heat your home. This is particularly true on warmer days. A heat loss calculation of the house should be done on a room by room basis. This calc should be compared to the amount of radiation you have installed. If this study indicates that the system water temp can be reduced to less than 140 for the majority of you heating system, a condensing boiler would be a could call. The temp would be reduced automatically by the ODR controls in the boiler.

Here is a great presentation‎

I do not think this forum is against combi systems.
Their good brands and not so good. Combi's work better in some applications than others.


Solution in search of a problem

@ June 20, 2013 9:38 AM in washing machine drain hose problem

The supply hoses present a much greater risk. The stainless braided ones are a good idea.
Even if (very unlikely) the waste line were to plug, it would only dump the contents of one load. A burst supply hose will flood the entire basement.
Even if you were to successfully seal the drain line, The waste water would just find another path. You would likely see it squirting out a sink or shower drain elsewhere in the house.
Good supply lines and a securely attached drain hose and you should be all set.
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