New system put in service today

[overdriv]

During the storm of the century, I started to heat water for my slab at 4:00 PM CT today. At 5:40 I had raised the floor temp 2*, from 43-45*.

I will keep track of it till about 11:00 PM and will take some pictures when the weather mellows out a bit.

 

[overdriv]

At 8:30 the floor was 49* and the air temp was 50*. Wow, it's warming up much faster than I expected.

 

[overdriv]

At 10:30 the floor was 51* and the air temp was 49*. Outside temp is 18*F.

 

[overdriv]

Here it is Thursday and the floor is 64* and the room is fluctuating between 55* and 57*. The room thermostat is set for 55*.

I checked it at 7:00AM and the floor was 64* and the room was 54*. So it finally got caught up some time Thursday morning.

At 1:30PM today I happen to catch it with the pump off and the water heater firing to catch up. The pressure in the system went to 72PSI before the water heater caught up and shut off.

System pressure is 48 PSI. Is it normal for the pressure to rise that much after the pump stops circulating? I have a check valve in the supply so it can't back up into the house.

Any comments appreciated.

 

[stingry]

Here it is Thursday and the floor is 64* and the room is fluctuating between 55* and 57*. The room thermostat is set for 55*.

I checked it at 7:00AM and the floor was 64* and the room was 54*. So it finally got caught up some time Thursday morning.

At 1:30PM today I happen to catch it with the pump off and the water heater firing to catch up. The pressure in the system went to 72PSI before the water heater caught up and shut off.

System pressure is 48 PSI. Is it normal for the pressure to rise that much after the pump stops circulating? I have a check valve in the supply so it can't back up into the house.

Any comments appreciated.

Since you are "trapping" the water in the system and it has nowhere to go due to the check valve, the pressure rises due to the fact that water expands as it gets hotter. You should probably have an expansion tank in this situation. You are somewhat protected by the pressure relief valve on the hot heater but having it pop off on a regular basis would tend to be a pain in the a**!

Cheers
Steve

 

[overdriv]

I wonder if I should get and install a pressure regulator. But then how would it regulate if there is no place to get rid of the pressure, as you said it is trapped.

 

[koditten]

Can you post some pictures?
From what I gather you don't have an expansion tank, with out the expansion tank in use the water heats up and expands, causing your pressure to rise because there is no place for the extra volume of water to go.

Expansion tanks are not that expensive. Having one will keep you from lifting the safety relief valve. Also you won't have to make up water that is dumped out the safety relief valve.

As for the pressure regulator, you should invest in one also. The one I bought for my system came with an anti-back flow valve included. I think it was like 80 bucks. I like having the piece of mind knowing that floor system water can't get back into my domestic system. I stated earlier in another post about how dirty the water in the floor system was. I did a flush on my system and could not believe how nasty that water was. I wanted no way for that water to get mixed up with my drinking water. I know you said you had a check valve, but the back flow preventer is a better way to insure the floor heat water stays out of the domestic system.

Welcome to the floor heat team.

 

[overdriv]

Yes, I'll try to get some pictures up tomorrow.

I do have an expansion tank, but no back flow preventer. How is it different than a check valve?

I do have it set up as an open system, but have yet to install the sink, which will use some of the hot water from the water heater. So really now it's actually like a closed system.

 

[Possum]

Maybe your expansion tank isn't large enough for the system? Did you calculate the size?

 

[overdriv]

Maybe your expansion tank isn't large enough for the system? Did you calculate the size?

I think there was something on the box that lead me to believe it was adequate size.

Also The initial fill was with very cold water out of the water tower so the expansion difference would have been greater than now.

Another question, and I know it's been asked before, but I can't find the discussion. How do I know what spped to run my 3-speed pump? So far I've been running on slowest speed.

 

[overdriv]

Here are a couple of pictures of my system.

 

[koditten]

I think you have a good looking system. I am wondering if your expansion (bladder) tank came pre-charged with 12-15 psi of air pressure. If the tank does not have air pressure in it the tank is useless. You need that space so the extra volume of water has a place to go.

 

[Steve NW Ohio]

Thanks for the pictures of your layout. It looks like you have 5 (?) loops, how large of an area are you heating?

 

[Alchymist]

I think there was something on the box that lead me to believe it was adequate size.

Also The initial fill was with very cold water out of the water tower so the expansion difference would have been greater than now.

Another question, and I know it's been asked before, but I can't find the discussion. How do I know what spped to run my 3-speed pump? So far I've been running on slowest speed.

Check the water temp going into the floor and at the return. If return water is too warm, it's running too fast.

 

[overdriv]

I think you have a good looking system. I am wondering if your expansion (bladder) tank came pre-charged with 12-15 psi of air pressure. If the tank does not have air pressure in it the tank is useless. You need that space so the extra volume of water has a place to go.

You got it, I checked the charge and it had zero pressure on it. I de-pressurized the system and charged it to the same pressure as the supply, 48PSI on the gauge. Then put everything back in service and it seems to be handling the expansion very well now.

 

[overdriv]

Thanks for the pictures of your layout. It looks like you have 5 (?) loops, how large of an area are you heating?

You're welcome. About 1100 sq.ft.

 

[overdriv]

Check the water temp going into the floor and at the return. If return water is too warm, it's running too fast.

I got the pump set on slow spd. and have throttled the flow down till I've got 90* water going into the floor and 72* water coming out of the floor. The floor is 64* and the room temp is 60*.

Does that sound close.

 

[stingry]

I got the pump set on slow spd. and have throttled the flow down till I've got 90* water going into the floor and 72* water coming out of the floor. The floor is 64* and the room temp is 60*.

Does that sound close.

From what I've read about radiant floor systems, it sounds like you have it dialed in!

 

[overdriv]

Well, my radiant floor heat has been in service for almost 5 years now. It has performed very well with 40 gal water heater, with a few exceptions.

1. Below 15*F the water heater fires 24/7 and still has a hard time mantaining a set point of 62* air temp in shop. Usually it sags the set point down to 60*. The water heater just doesn't put out hot enough water to catch up.

2. Twice a heating season I have to clean the rust out of the burner area and usually replace a thermocouple. That rust is off the bottom of the tank. I'm talking half a coffee can or more of rust. I'm scared it's going to start leaking or worse.

3. Using it as an open system was just not practical. I know, you guys told me so. During the heating season it worked out fine. But for just occasional hot water in the non-heating months, it just wasn't practical to have the water heater setting there maintaining that heated water. Just didn't use it enough. This probably contributed to the rust on the bottom of the tank.

So I have removed the water heater and installed a Navien combi boiler. It has a separate section for DHW on demand. I still have the city water connected to the DHW inlet and the make-up inlet for the floor heat section. The floor section is now a closed system and it seems to maintain about 10PSI on my gauge, the front panel says 14PSI.

I just put it in service today. I installed it with the HVAC guy I bought from supervising me. He stopped by today and wired up a relay off my Taco to start the Navien when the room thermostat calls for heat.

I have the outlet water temp set to 120*. Floor temp was 60*. Water back from the floor is at 85*. Room air temp is 64*. Thermostat set point is 65*. Weather has been very mild here for the past week. Still it's low 50s during day and high 30s, low 40s at night.

We will be connecting an outside thermostat to the unit later this week. I'm hoping it will be able to maintain 64* as that is my comfort zone while working in shop.

Comments are appreciated, pictures to follow in a few days.

 

[kabinenroller]

When I heated my first shop with hydronic I had a 40 gal electric hot water heater, it could not keep up with the demand for heat. (60 degree setting, 750 sq. ft. Space) I then converted to a propane fired unit and it worked well unless it was zero outside.
My new building is 1,600 sq. ft. And I have the thermostat set at 60, I use a wall mounted propane fired hot water heater. The system runs at 12 psi. This system works great, The heater very seldom runs and when it does it recovers the water temp. very fast. I beleive the key is how I insulated the building, foundation, and slab. I have six loops, one zone.
Your new boiler should work fine, I think you will find 64 degrees might be just a little too warm, if my shop gets to 63 while I working I find it almost too warm.

 

[mygarageone]

Your system should not be over 12-15 psi , which means you have a high pressure relief valve , replace it with a 30 # unit and put a press regulating valve on the feed.

 

[overdriv]

I do have a 30# PRV on the floor side and a high PRV on the DHW hot outlet. Instructions read to provide 40PSI minimum to make-up and DHW side.

Yes it seems to be running between 10-15PSI, floor side that is.