we have a manufactured home. the water heater is on the outside and faces where the cold wind blows. the hot has been freezing when it gets below ten degrees. the pipe out from the top is insulated and the insulation underneath is intact. what are some thoughts on how to prevent this from happening....

 

So it's the incoming cold water feed to the hot water heater that's freezing . . . . down below in the crawl space, before it gets to the HWH ?

Heat Tape ?

 

The cold water runs fine. Just nothing coming out of the hot. I don't want to cut into the insulation underneath if it can be avoided.

 

I think you need to first identify exactly where it's freezing. The cold water line feeding the heater right there in the room is a possibility as is the line below in the crawl space especially if you have foundation vents.

Insulating the cold water lines is a good start. It will not prevent freezing if you go away for a week and don't use any water but it could easily be enough to get you through the night or days while away at work and not using water.

Is there an electrical outlet nearby? If so heat tape

 

All of the water is "cold" before it gets heated.

 

Make sure your hot water line ( the one that exits the tank) is insulated as well as the cold. I am assuming the cold feed line as well as the hot return line are under the home to feed the other areas. Check for any small cracks or holes where the wind can blow in. Most times it is a breeze on the pipe that causes it to freeze. And yes, hot water does freeze faster than cold water which is why it is usually the hot water lines that freeze up.

 

the cold water is the white pipe on the right? The hot coming out is the insulated one on the left? the pipe at the top is hot. do you think the pipe wrap is not enough for that one? there are two vents in the door that don't help. I have put heat tape on the pipe on the right but the hot water still froze below 10 degrees. should I heat tape the other pipe? I believe that would tell us it is under the floor?

 

Usually, both the hot and cold feeds come out of the top of the tank. The cold feed line in your picture should be the line going into the tank about two feet from the floor with the 90 degree elbow on it. The one above that and to the right is your pressure relief valve. No water should be coming out of that unless you have a problem with the tank. The stainless steel flex line that is insulated coming out of the top of the tank must be your hot water return, although I have never seen a flex line like that coming out of a tank.

I would cover up those vents in the door. I see no reason to have them there. Also insulate the cold water feed. It looks like that is right behind the vents in the door which would make it very likely for it to freeze up. Also if possible, take a look at the lines under the floor and make sure they are insulated and there is no way for air to blow on them.

 

MH water heaters always have one of the water lines about 2/3rds of the way up the tank ... I don't remember if it's the cold or hot line I agree with closing off the vents.

 

Interesting. 99% of the water heaters in my area have both hot and cold lines on top. The cold line has a dip stick in the tank so it is feeding the bottom. The cold feed should always be the lowest feed in the tank even when the feed is on the side.

 

Keith..... that's a gas water heater. Needs combustion air.

I have a feeling the installer was trying to use thermosiphoning to keep the lines from freezing. That would be one reason to tap the tank lower like that.

 

You may be right PJ, but that looks like a direct vent heater which would get its combustion air from the chimney vent.

 

both lines go thru the floor at that point. the rest are under the house covered with insulation and sealed in black plastic. The skirting is cinderblock so I don't think any direct wind is getting in. I wonder if I can block one of the vents. I wonder if there is something that can heat the floor where they go thru.

 

That's what I was thinking.

If that door with the vents is actually outdoors facing the elements that place wasn't made to be in cold climates and the space the heater is in looks pretty tight.

If my guess is correct you're gonna have to find another place for combustion air then seal and insulate that door.

 

I think that's a B vent..... double insulated. Looks like a standard water heater or it would have PVC lines.

 

Yes, for this climate, the outside vent is a bad design, especially when it is facing the wind. I am sure I can vent it through an inside wall. That might be best in the long run. Then insulate that door to only be opened to replace the heater. would it still help to heat tape the long pipe on the left?

 

As stated you need the vents.. Do not block them..

That is a manufactured home water heater.. Most are side tapped.. That is normal..

You dont know what line is freezing.. It could be the cold since it has no insulation.. Even if you have cold elsewhere in the home, that white cold line if it froze there would stop the hot water flow...

Insulate the cold line too..

Heat tap would be a good option before you insulate the pipe. They are thermostatically controlled..

Another option during cold spells is to run water out of a faucet with a small pencil stream. Moving water has a hard time freezing...