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The Wall


Joined on January 19, 2012

Last Post on August 30, 2014

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How low can you go?

@ February 10, 2012 9:29 PM in Air gap or no air gap.

Tell me more. I assume you are still doing an air space. How big? Foil faced insulation? Pex al pex?Most importantly how does it do at low temps?

Trying to by a Dumptruck at the Ferrari dealership

@ February 10, 2012 7:26 PM in Help please

Do you feel like you are trying to buy a dumptruck at the ferrari dealership. The wall is filled with wetheads who want to build beautiful high performance machines. The idea of forced air is distasteful to many. The coal powered beast you are suggesting is unthinkable. To answer your question. 90,000 BTU should be pretty close. I think you need a few ducts or at least vents cut in the first  floor. You could use thermostatic grill fans. I think carries them. How does the stoker get it's combustion air, is it from the room or ducted in? I am curious about the economics of this. Do you know what you local gas (or propane),electric and coal costs are?
"Coal stokers are nice. but what would it take to get you into a shiny new Mod/Con with pretty European panel radiators" 
Best of luck

The customer is always right?

@ February 10, 2012 6:46 PM in newbie

I have to agree with Icesailor. My motto is "The customer is always right" "Unless of course they are wrong" You are the professional and will get the blame when it does not work correctly. The customer will always conveniently forget it was their idea. I the case of this system need to explain the health hazards and design the correct system.

Double Bubble

@ February 10, 2012 6:34 PM in Air gap or no air gap.

I think it is fairly widely excepted that double bubble as insulation is voodoo. I would never consider it under a slab. I do believe it has reflective properties which are helpful in this installation. Just as foil faced insulation will help reflect the energy in the air space so should double bubble. I would however install fiberglass insulation to reduce downward heat loss. It would have been cheaper to put in foil faced fiberglass, but since you have double bubble what the heck. Don't forget to insulate the snot out of the rim. I would at least put foam in the cracks and snug fitting batts in the bays.


@ February 9, 2012 8:31 PM in Does anyone know of any piping method

The tekmar controls can do this. The tn4 335 controller will cycle the zone valves to provide a lower average temp to a particular zone. These work well in houses with different types of infloor heat.


@ February 8, 2012 11:46 PM in a separate flow check valve or a circulator integrated with a flow check valve?

The integrated checks are "spring checks" and are similar in design to most flow checks. They appear to be less robust. That being said I have had very few problems with them and the don't appear to increase the cost of the pump.


@ February 8, 2012 11:41 PM in flow check valve and swing check valve

I don't think I have had a conversation that started with "the guy from lowes said..."that ended well. As the previous poster mentioned they are not the same. Flow checks or "spring checks" provide a tight seal against ghosting and most inadvertent flows ,they can be mounted in any position. They have the disadvantage a fairly high resistance to flow. This can be a disadvantage in some mixing pump situations.
Swing checks should only be mounted horizontally and are prone to ghosting  in many applications. They have the advantage of comparatively low resistance.

Do you have a picture?

@ February 8, 2012 11:19 PM in Air gap or no air gap.

My first thought is to run the outdoor reset curve in the boiler. You can put the DHW tank on priority so it won't be effected, if it is plumbed that way. Do you know if your mixing valves are thermostatic?If they are not you could make the staple up loop match the boiler curve (wide open) and the slab loops "lag" at a lower temp. The performance of your staple up will depend greatly on your heat loss.I have seen similar systems perform fairly well up to 15 BTU/square foot. Above that they tend to struggle.
Your title makes me wonder if you have  closed this up yet? If you still have access I would keep the "double bubble" 2" away then insulate the rims very well I would also add at least r-15 ideally r-21 fiberglass underneath. It looks like the lower level is set up really well. You don't want any downward heat loss.


@ February 8, 2012 1:32 PM in type L or type K copper pipe for water heating?

I think the info you found is for underground water service. "K" is a thick walled soft copper that comes in a roll. "L" is thick walled and in my area is used for heavy commercial/industrial applications. I don't have experience in every part of the country, but I see "M" 99.9% of the time.

Detailed drawing

@ February 8, 2012 11:24 AM in Need plumbing help

If you post a detailed drawing or picture including pipe sizes,heat exchanger specs,pump sizes ect. You can probably get some help here. Pipe sizes are very important. For example each of your 1/2" loops should have a flow rate of at least .75 to 1 gpm. It sounds like you have 8 of them (6-8 gpm) fed by a single 3/4" pipe (4 gpm max.). I think if you really want to get this thing figured out you need to learn some fundamentals. Another (free) option would be to go to some of the manufactures web sites and take video tutorials. Taco has some good stuff in the "flow pro university", Many of the solar companies have sample layouts that provide a good starting point.

Stop and regroup

@ February 7, 2012 11:26 PM in Need plumbing help

Please don't take this the wrong way, you need help with this.
I checked out your posts on the solar side.
I think you have a couple of choices.
You could hire a professional designer to do the necessary calculations and design this correctly.
You could take a break from working on this a read a good book on hydronic design. I like Modern Hydronic Heating by Seigenthaler, there are plenty of good ones out there.

The first thing you need to do is calculate the output of those solar collectors. Then you need to size the pipe (in copper)  to the array. The correct size for 120 evac tubes is not 3/4". Next you need to figure out how to store the energy. Dumping it into a concrete slab all summer seems like a waste of collector. The efficiency curve of the collector is also an important factor in your storage calculation.

On the heating side you need to calculate the load of the heat zones (based on the heat loss of the building and the size and temp rating of the emitters) The pipe and pipe size is then calculated. You cannot service 2500 square with 3/4" pipe. Then comes the heat transfer. The heat exchangers in the solar tanks need to be sized for the heating load, as does the back up heat.

Your drawings lack many critical components including expansion tanks, air vents, check valves ect. It is so important to remember that water will never go were you want it to. I will only go were you make it go.

I absolutely love your passion for DIY and solar. I can tell you from experience. It is time to regroup.

Basement heat

@ February 7, 2012 2:14 PM in Hydronic floor heat

Sounds like a great way to heat the basement. The upstairs may get a bit warm also. Seriously, it might be time to find a new heating guy.There are tons of posts here describing the pro's and cons of different designs. Heating a an uninsulated basement ceiling is not one of them.


@ February 7, 2012 1:48 PM in radiant heat loss because of pex placement?

Your boiler can produce the same heating curves your blocks presently do. You might decide you need 150 on the coldest day and 100 on the warmest. Your boiler will start condensing and approaching peak efficiency if you can return water that is cooler than about 130 degrees. It is not a big deal if you don't condense on the coldest day, but ideally your boiler curve will allow condensation on your "typical" heating day.Check out this Ashrea presentation and you will see what I mean

The rest of the answer

@ February 7, 2012 12:36 PM in radiant heat loss because of pex placement?

The boiler can be set up to manage the outdoor reset.The actual output temperature of the boiler will be what is calculated for the heating load just as the mixing blocks are doing now. The (secondary) heating loop with the alpha circulator will tie into the main boiler loop using closely spaced tees or another "hydrolic separating" method, similar to the way the mixing blocks are now.. You will still need your primary boiler circulator. I am not sure whether the primary boiler pump needs to be upsized. It sounds like it is smaller than spec, but is working.That boiler is designed for more of a high head circulator.The safe move would be to replace it.This approach should allow the boiler to run more efficiently and reduce your pumps from 5 to 2, saving quite a bit of electricity


@ February 7, 2012 10:59 AM in radiant heat loss because of pex placement?

I believe Gordon's recommendation is "spot on". Yes the grundfos alpha can easily handle the load. It may take a bit of trial and error to get it dialed in.

It's a delta P

@ February 6, 2012 11:22 PM in grundfos alpha pumps ???

The alpha does not read the temp. It works off a delta p reading, it comes up with electronically. It won't function well in "auto adapt" mode when switched because it resets what it has "learned" when it is powered off. I like to switch the pump and put it in constant pressure mode. Never had a problem.
This is not a delta t pump. Taco and others make some nice delta T's for that.

Mod con

@ February 6, 2012 10:57 PM in Replacing Open Hydronic System

I am assuming the 40 gallons tanks were the heat source and are tired? My first choice would be a firetube mod con for the heat with an indirect tank for DHW. I think there are some potentially great combi units out there, I have to agree with icesailor that they are largely unproven.

Thank for the info

@ February 6, 2012 10:46 PM in Navien Combi Boiler

This looks like a nice little unit. I think it would work nicely in many applications. The hot water capacity is robust. At 5 Gpm and 20 delta T it gives you 50,000 BTU for heat.

Check with the manufacture

@ February 6, 2012 5:53 PM in Carpet placement with radiant baseboards?

Your baseboards have been designed to perform with a certain air clearance.Less clearance will reduce there ability to convect air  and thus heat the room. I would check the manufactures literature and move them up if needed.If you are off by 1/4" I probably would not bother. 3/4" I certainly would.

Check my math please

@ February 2, 2012 11:41 PM in How to calculate COP on air source heat pump.

Xcel energy in Colorado claims to be 30% efficient.Including plant inefficiency and line loss.

 A typical ground source water to water heat pump in this area has a COP
of about 3. This would give me an overall efficiency of about 90% using
a mix of  generator fuels,primarily coal.

If I install a Natural gas condensing boiler I should be able to achieve 90% overall efficiency.

Why would anyone spend the resources to do a heat pump in this area? Am I missing something?


Check my math please

@ February 2, 2012 3:59 PM in How to calculate COP on air source heat pump.

Xcel energy in Colorado claims to be 30% efficient.Including plant inefficiency and line loss.
 A typical ground source water to water heat pump in this area has a COP of about 3. This would give me an overall efficiency of about 90% using a mix of fuels,primarily coal.
If I install a Natural gas condensing boiler I should be able to achieve 90% overall efficiency.
Why would anyone spend the resources to do a heat pump in this area? Am I missing something?

Open Radiant

@ February 1, 2012 1:17 PM in Legionnaire's fopund at Luxor in Vegas

I few years ago I replaced an open radiant system in a very high end home. The slabs were heated by remote gas hot water heaters located around the home.The slabs never performed well  and the water heaters only lasted a few years due to the fact that they never saw water over 110 degrees.I was struck with amount of bio-mat that was lining the pipes in both the radiant and DHW pipes. It took a significant effort to clean them.
I wonder how many "mystery illnesses" are caused by this and are going undetected.
Interestingly the legionilla  bacteria is not harmful to consume but infects our lungs while showering.
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