Joined on January 19, 2012
Last Post on April 15, 2014
@ June 20, 2013 12:48 AM in High Efficieny Gas Boiler RecommendationHenry,
I love the turntable. Where is the spring?
I have always wanted to pull into the garage at 60mph. the energy would be absorbed by a giant spring. The car would be spun on a turntable and be released at 60. No wasted energy. Your project is so close.
@ June 19, 2013 5:22 PM in makeup water problemIs the fill on the suction side of the circs? Where is the expansion tank located? Do you have a relief valve?
I was thinking that if the circ is pumping towards the tank. It would lower pressure on the suction side causing the fill valve to open. When the circ turns off the pressure would stabilize at a higher pressure triggering the relief valve.
Just a thought,
@ June 19, 2013 5:15 PM in DumbI had a rep that changed supply houses. When you called and asked for him at his old job they would give you his phone number at his new job rather than introduce you to your new rep. Crazy stuff!
@ June 19, 2013 5:08 PM in Which boilerYou have no other choice but oil (or you own an oil well)?
Here is a handy tool to help evaluate fuel costs.
As far as sizing goes, the heat loss number is the one to look at. You certaininly do not want an oversized unit, particularly a low volume oversized. The short cycling will be amplified.
@ June 19, 2013 8:45 AM in in slab radiantJoe,
Check out this www.pugetsoundashrae.org/PDF_files/AshraeCondensingtechnology.pp
The trick with your system is to get the return water below the dewpoint. Your cast iron rads may perform better than you think at the lower temps. The simplest piping design would have the entire system designed for the same boiler temp curve. You will get pretty good efficiency .If the coldest design day can have return temps less than 130.
Your garage floor would be a bit overheated at that temp, the warm board system would depend on the design. A simple non-thermostatic mixer would allow you to have a zone temp that simply "lags" the boiler ODR curve.
I did not realize that you had a condensing boiler. That changes things.
@ June 18, 2013 1:33 PM in Hard or soft: what water to feed into Hydronic heating systemI would check with tech support to get the definitive.The salt can be worse on the stainless than hard water.
In the past we have just filled buckets with treated city water. I guess you could buy drinking water also
@ June 18, 2013 11:01 AM in Hard or soft: what water to feed into Hydronic heating systemLochinvar should have a water hardness number in the manual.
Depending on the size your system, I think it would make sense to truck in a few 5 gallon buckets for the original fill.
@ June 17, 2013 11:19 PM in Triple Aquatat RElayYou really need to post the model of the boiler and a diagram of how it is wired.
@ June 17, 2013 6:44 PM in Delta t ...... The obsessionJean,
'It sounds like you have your shortcycling under control. I suspect there is a flaw in the way you have measured your delta t on the system side. It would be impossible to get the delta t you describe without short cycling.
Delta t should be carefully considered at the design phase. Not obsessed in the real world.
Glad your system is running so well after the tweaks.
@ June 17, 2013 9:07 AM in Delta t ...... The obsessionI am not really suggesting you heat with light bulbs, just making a point.
As I indicated earlier, I don't obsess about delta t.
Radiant loops have so much resistance that it take an enormous amount of energy to significantly raise the gpm. I do not think there is a circ out there that has a pump curve that would allow a range of say, .5 to 1.5 gpm on a 200' length of 1/2" tubing. I personally do not think that radiant loops are a good application for delta t circulators. They will work quite nicely on a series baseboard application.
I also don't think that the nearly constant circ setup you have is very efficient, it has nothing to do with the speed of your circulator. You have said that your boiler is oversized, I assume you do not have a buffer tank. I appears that you are running your boiler in a short cycle condition most of the day. If you turn the reset curve up a bit, the boiler and circ will run less hours with longer cycles. I would be surprised if this has any effect on comfort. I believe your overall efficiency will be improved. You will have less hours of boiler heat loss, less electricity used by the circulator and boiler, and longer more efficient cycles. Raising the temp will reduce the amount of condensation slightly, in my opinion not enough to be concerned about.
@ June 17, 2013 12:37 AM in Delta t ...... The obsessionGordy,
Thanks for starting this one. I agree with you that it is a design constant. In the real world it will vary all over. A startup on a cold slab will be a higher delta t. Out door reset will lower the delta t. Some of this can be corrected using ecm or other controls. I also think that to some extent, who cares? If a system has a delta t of 15 at cold start up on cold design day, then stabilizes to 10 is it a problem? If the same system drops to 4 when the boiler temp is lowered on a warm day is that bad? I think it is completely normal.
A system with a delta t at zero or one is not giving off any heat unless you are pumping the crap out of it. If you loops are circulating 3 gpm at 1 degree you are giving 1,500 btu/hour to the space, not including the heat lost in the piping and circulator. You could turn on 8-60 watt light bulbs or invite 3 people over and generate the same amount of energy. I think you are wasting energy pushing cold water around the house.
@ June 16, 2013 8:28 AM in in slab radiantJoe,
So sorry your post turned into this ridiculous debate. Please post again if you have more questions.
Jean-David if you have a delta of anywhere near zero, your curve is set too low for your install. If you are just interested in wasting electricity only to gain a little heat, why not just leave a light bulb turned on? You could even put it on a t-stat. The end result will be the same, you just won't wearing out expensive boiler components. Highjacking threads for this kind of nonsense is rude and counterproductive .
@ June 15, 2013 11:10 PM in BACKFLOW PREVENTER vent dripThe backflow preventer is designed to vent when domestic pressure drops below system pressure.
If you install a spring check upstream of the backflow valve, the problem will be solved.
@ June 14, 2013 5:52 PM in High Efficieny Gas Boiler RecommendationYour system clearly works. You are saving energy over a conventional system.
The 10 to 1 turndown on most units costs some efficiency you are less efficient than a 5 to 1 model in most cases.
Navien does not have a particularly good track record over the long hall. They are priced accordingly
@ June 14, 2013 9:11 AM in High Efficieny Gas Boiler RecommendationI don't subscribe to the strategy of oversizing the heat boiler in order to get instantaneous DHW . Just to many compromises. Navian is a completely different boiler, much lower quality and price point.
@ June 14, 2013 8:58 AM in in slab radiantIn real operating conditions, delta t will vary tremendously. Tubing in thick slabs will have higher variations. Low mass applications will be more stable, as Jean-David said they will be tighter as the water temp approaches the indoor air temp.
Delta t circulators help stabilize this somewhat but nothing will completely stabilize it.
I guess I don't see a problem with these fluctuations. If your slab starts getting too wide a range it will create hot and cold spots this can be avoided with proper circ sizing and shorter tubing loops.
Why not design the radiant for a cold day design of 10 degree delta t and figure it will usually be a bit tighter. You have to pick a number as a basis for your design ,10 for floors and 20 for convectors seems to work pretty well.
@ June 14, 2013 8:33 AM in Kitchen heatRadiant floor heat does not have to add weight. Take a look at warm board.
Heating the countertops would be another option. If the tubing cannot be poured into the top, they could be attached the underside with joist track.
Kickspace heaters could be sized to do the job, It just is not as nice.
@ June 14, 2013 12:52 AM in High Efficieny Gas Boiler RecommendationThe first thing to understand is that number of BTU's that your coils are capable of emitting is not the same as the number of BTU's your house will loose on the coldest design day(heatloss calc). Your boiler should be sized for the latter.The home you describe should come in at less than 20btu/ft.
High efficiency boilers perform best with low water temps. The entire system should be designed perform at low temps. It may be that your designer has oversized the coils to achieve this.
Trying to integrate forced air and radiant floor heating is tricky.The whole idea with the radiant is to have warm toes. If you keep the floors warm for your feet, you really don't need the air.
The heat exchanger in the lochinvar is "hands down" superior tovAlpine
Given the scale of your job, and the fact you are still in the design phase, I would get a top quality contractor on board now and rest easy. There are several great long island guys on this site, I would start with Robert O'Brian.
@ June 14, 2013 12:10 AM in summer/winter hookup & oil furnace running when no water is being usedA picture would help. It sounds like you have an indirect coil and your boiler is designed to be always hot.
@ June 13, 2013 11:48 PM in solar heater controlYou are looking for something like this?
You are trying to turn on a circulator when the difference between 2 sensors reaches a certain temperature?
Post a drawing or picture if you need help confirming compatibility.
@ June 13, 2013 8:54 AM in in slab radiantJoe,
1. Shorter is better on the loops. I my mind 200' should be the target 250' the max. Keep the loops within 10% of each other. This will keep your head loss within the range of all the affordable circulators.This also keeps the delta t low and provides a nice evenly heated floor. Everyone will have a favorite, the grundfos 15-58 works well for this application.
2. The mixing is a tricky question. You could use "dumb" mixing valves and just let them "lag" the ODR setting your boiler is firing. It would be better to give them individual "smart" control. You could use either an injection mixing setup or a mixing valve with a controller. They both have pros and cons and I would let the tie in with the existing system dictate. A smart mixing setup would also allow you to prevent cold water from returning to the boiler when the garage zone is running. If this happens it will cause the boiler to condense, this will shorten it's life considerably.
3. Approx 10" spacing would be plenty for a garage.Again shorter loops.
4. Warmboard is a good idea. You will not have much flexibility on tubing layout so it would be good to have good control over the water temp in order to "tweak" the output.
5.You do not need multiple air scoops. Be sure your existing one is in the optimal position in your system. If the expansion is attached to it, the circulators should be "pumping away".