New House Build

   / New House Build
  • Thread Starter
#191  
My wife Terry will be very disappointed that I posted garage pics with the floor dirty. I took those while she was gone. :)

Proof to Big Barn that we do have dirt in Missouri!!! :D
 
   / New House Build #192  
Somebody likes plants:)
 
   / New House Build
  • Thread Starter
#193  
   / New House Build #194  
Excellent post Mike. Thanks for taking the time to write it.

The guy that installed my HVAC also lives on a slab with floor heat. He said he uses his Air to Air Heat Exchanger system to heat his house until first frost. Then he fires up the floor system. When grass starts to green in Spring he turns it off.

He also said that his thermostat setting changes as Winter goes along. I didn't do that last Winter in the shop. But I don't want it to be as warm out here. Becomes too hot to work.

Friend of mine has the same open system as yours. He really likes it. All my water system is located in the same Mechanical Room. My floor heat system could be changed to work like yours fairly easy. I discussed this with the installer. He didn't really have any negatives about doing that. Just said let's try it this way first and see how you get along. Only part about it I don't understand is, I turn on the shower. Water from my floor loop would feed my Tankless domestic heater. So, in my case, my floor heat system would kick on because it detects movement. Aren't I going to overheat my floor if a couple showers are taken close together??? Maybe I don't understand exactly how everything is plumbed. So my floor heat system has to heat 55F degree water coming into the house from outside rather than maintaining a temp in the slab??

I am using an Azel thermostat in the shop. It's the one with the slab probe. I am going to investigate the Wirsbo thermostat. Thanks for mentioning it.

You didn't mention how you are heating your floor water?

Thanks again for your input. Good stuff!!!

You're welcome. Your latest pics are giving me garage envy, we may finally add one in the spring.

As for the questions, my system whenever there is a hot water demand will have the water heater fed from the floor loops so it will be preheated making that part more efficient. I would assume you'd have a floor temp drop but I can't notice it and if the temp drops the thermostat will kick on. Could be the slab probe would notice it but the air side of the thermostat may tell it not to run. If it does then the preheat savings may be a wash. From what I understand, this is how all open systems work as you need to run fresh water through the system to make sure you don't get stagnant water which could breed legionnaires disease. As for the summer mode, when I switch to that all water coming into the house goes through the floor loops first so cools the floors and warms the water. No sweaty pipes. :D

My water is heated with a Bock oil fired water heater. My wife is afraid of gas heat so this was the best option and it is pretty efficient. It heats all our hot water and is super fast at heating it.
 
   / New House Build #195  
Our winters don’t get as cold as yours Richard, but a properly heated shop really appeals to me as I get older.

Thank you for posting all the great info.
 
   / New House Build #197  
:thumbsup:
 
   / New House Build #198  
Very nice. Is the third building an original machine shop?
 
   / New House Build #199  
Nice how the house and other buildings all fit together on top of your hill.
 
   / New House Build #200  
First off, nice work on the house. We did stained concrete for the lower level here - kind of a dark leather brown color that came out nice. I think it is a good solution for slabs.

Radiant floor heat - my experiences. I started off thinking an on-demand HW heater was a great solution. I no longer really think so. There are caveats to that, but what i ran into has soured me on them. I have 3 Takagi on-demand heaters. 2 in the house, 1 in the shop. The 2 house ones are very high efficiency (96-97%) and one is dedicated to domestic HW and the other to radiant floor heat. The one in the shop is slightly lower efficiency but still decent (low 90's?) and only covers radiant heat. From the get-go they have some great advantages - small footprint, the ability to do sealed combustion with PVC venting, high efficiency and very simple controls (your T-stat asks for heat and starts the pump, so the heater automatically starts with teh flow from the pump).

HOWEVER.....

I have learned that these are SUPER sensitive to hard water. We moved in Aug 2015 and did not have a softener in yet. It was on the do to list but I didn't consider it urgent. We started having a lot of issues with hard water plugging up the shower valve screens so finally in Nov 2015, I put in a softener. That fixed those issues and i figured we were good. The next year the domestic HW heater started to leak. Tech support was very helpful and they were nice enough to comp me a heat exchanger, which I had to install (THAT was fun...NOT!). They diagnosed it as due to hard water. Now we ran hard water through it for all of 3-4 months at most, then fully soft water, but that was enough to kill it. I had lengthy technical discussion by phone and email on their diagnosis, and it was clear they were right. I bought a good hard water kit and found my incoming well was 24-26 grains hardness. After softening, it was <1. We have not had problems since, for the past 3.5 yrs.

Radiant had the same issue as those heaters got filled with hard water prior to the softener. The one in the shop crapped out this past spring after only ~5 yrs use - same issue as the house DHW. The one in the house is still going (3-4 yrs) and I did flush it with vinegar to see if I could stop the hard water build up. So far it is OK, but who knows if it will die soon? The other wrinkle is antifreeze. Now this depends a lot on where you live. Up here, if the power went out and it got really cold, I would be at risk of freezing the system after sufficient time down. Can't take that risk so I added 50% antifreeze that is designed for radiant systems to both house and shop. I didn't do that right away but when i did things got worse. I start to hear a low grumbling vibration from the heaters when running. This is cavitation that is happening in the heat exchanger due to the antifreeze mix having lower thermal conductivity than straight water. It is bad for the life of the heater. I can improve it by raising the system pressure. Most in-floor radiant runs at 15 psi, but I run 25-30. It still does not quite eliminate it. You also have to up the pressure in the expansion tank and any relief valve to match when you do this. If you are not running antifreeze, you will eliminate part of this issue, but not the hard water issue.

The next time i have to replace one of these, I am going to find a small conventional tank heater and put that in instead. I believe that will improve things but i will lose floor space. Time will tell.

My $0.02
-Dave
 

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