Hot Topics: Steam Boiler, Cold Water

A steam boiler in a basement.

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Winter weather still dominates the forums. This time around, what do you do if your hot water comes from the same place as your home heat, and neither keeps you warm enough? One member has a steam boiler, a tankless water heater, and still can’t get enough hot water to take a shower. The other members step in to show him why.

Original Post: Tankless Water Heater--Cold Showers please help me, my gf is driving me nuts!

mdr411 Member

Hello everyone, I found this site after scouring the internet for a week looking up info. This site is by far the best I've seen so I decided to join. I have read many posts here but I have a couple of questions that I haven't found the answer to.

So here's the problem. We recently moved in to a home that has a Wells McClain boiler, we have steam radiators for heat and what I think is a tankless water heater because we don't have a tank. We use oil for fuel. The main problem is with showers not staying hot long enough. So far what I've done is turn up the little temp dial on the side of the boiler. There is a little gray box on the left side of the boiler with one screw holding the cover on. I took that off and noticed a dial with temps on it. I assumed it was the water temp and turned it up. While this did help the water temp at first, the radiators started getting really hot and heating the house up higher than our thermostat was set. It was at this point that I realized that I must have changed the wrong setting and put it back.

Last night I went down in the basement and I found the mixing valve, which is set on 180. It's only a little brass knob and it only turns a quarter of an inch so I did not move that. Then I noticed that the pressure gauge on the front of the boiler reads zero. That probably shouldn't be zero, right? One last thing I noticed. When we moved in they told us to drain the rusty water and refill the tank every week. We were told to use the little glass vial on the front to see the water level. The problem is the vial is so rusty I can't even tell what level the water is and/or whether or not it is full or empty. The last time I drained the water and re-filled it was around the time the hot water problem became worse. Could our lines have too much or too little water? Sorry for all the info, I just wanted to give as much as I could.

Highlights from the Thread:

NJ Trooper Forum Topic Moderator

The 'thankless' coil method of producing domestic hot water is better than only one other way... a kettle of water on a woodstove. It is the most inefficient way of producing hot water in a home. Talk to anyone who has one and you will see they all have the same problem to varying degrees.

First problem... the inside of the coil gets 'limed' up with mineral deposits, more and faster if you have hard water, and this reduces the heat transfer and flow rate which ultimately leads to cold showers.

Trying to flow MORE water to compensate will only make matters worse. Next time you are facing a cold shower, turn the water flow DOWN and I think you will see that it gets hotter. I know that it's counter-intuitive to do so, but try it and you will see. It has to do with the amount of 'contact time' that the water in the coil has to pick up the heat.

180 is EXTREMELY HOT for domestic hot water, you can win a trip to the emergency room pretty easily. Young and tender skin, and elderly slow to react are most vulnerable, but ANYONE is in danger of SCALDING injuries!

“I noticed that the pressure gauge on the front of the boiler reads zero. That probably shouldn't be zero, right?”

On a STEAM boiler, that is perfectly fine. The only time that you should see any pressure on that gauge is during a heat call when the boiler is actually making steam. All other times it should return to zero when the boiler cools.

You should not have to drain and refill the boiler every week. Perhaps they were instructing about the WATER FEEDER or the LOW WATER CUT OFF devices on the side?

The vial (we call it a 'gauge glass') can (and probably should) be removed and cleaned. You NEED to be DILIGENT about maintaining the water level in your boiler! Not doing so can result in a cracked boiler, or FIRE if the boiler is fired dry.

The water level in the boiler itself MUST be maintained at the proper level! If you over fill the boiler you run the risk of 'flooding' the system... that's always fun... NOT! You will want to take apart and clean this gauge glass so you can see the water level.

mdr411 Member

Thanks for the tips. I think I will work on cleaning the glass first, although I am afraid it will crack so I'll have to order a new one.

My other question is should I install a new coil? Is that something a newbie like myself can do? I'm comfortable with plumbing a soldering and I do all my own work on the home but heating is new to me. I definitely want to learn it though.

NJ Trooper Forum Topic Moderator

Be careful and you won't break it, that stuff is pretty tough. Inspect for cracks and replace if found. You should plan on at LEAST using new washers and these you may be able to find at a well-stocked REAL plumbing/heating supply, probably not at HD or Lowes.

I don't think cheap enough to keep one on shelf as a spare... but then I'M cheap, you might not be!

mdr411 Member

OK so I figured out the problem... low water level. Due to the gauge glass being so dirty I could not see the level of the water. So I added more and more water until the boiler started up again. I held a flashlight to the gauge glass and after a while I could barely see the level rising through the rusty glass.

Now we have the thermostat set at 55 and the house is warm because the radiators are working again.

Find out if mdr411 needs to replace the coil, and about asbestos abatement at: //