New Boiler - Steam Heat

Go to the Wall for your steam questions.

I'm not familiar with residential boilers and there may be some truth to it. Check the manufacturer for recommendations.

Every industrial boiler I've ever seen or operated has a blowdown valve. Proper blowdown is one of the most important parts of operating high pressure boilers. I'd also opt for the auto fill valve.

The amount of blowdown will vary with the amount of sediment and the amount of make up water used. Water has minerals and when made into steam, the minerals stay behind. If some steam leaks, more water cmes in and brings in more minerals. After a time, the minerals build up as solids. If the total dissoved solids gets too high, operation of the boiler is affected.

Actually, cleaning a residential steam boiler is a lot more important than just removing water sediment from "a little" steam loss. The single pipe systems (a majority in NE) are vented at the radiators, i.e. there is always steam loss during the heat cycle, so quite a bit of water is added to the system. This is why some people prefer steam systems over HWBB because the air humidity is kept higher. Then, during the cooldown cycle the system is vented and air is allowed into the pipes. Moisture + oxygen + heat + black iron pipes = a ton of corrosion junk in the boiler. I usually drain a pound of muck from my boiler every month.

Looking forward to radiant floor heating next year,

EJ

Your installer should have given you an owner's manual with the new boiler. If you check it Iam 100% certain that it will include instructions on draining the boiler and the location of the valve. If it is indeed missing, call your installer and have him finish the job.

Boilers have a sensor as you describe and they must be blowndown on a regular basis. Some have two sensors. One will turn the water on when the level is low, the other is strictly a safety to shut the boiler down at a low water level. It is set a bit lower than the first and is a backup if the first one fails.

Boilers should also have a blowdown valve at the lowest point to flush out sediment.

Yes, except that the lowest point blowdown valve is really just a drain valve, I think. On my two-pipe system, the drain valve is on the water return pipe just where it goes back into the boiler, and I have converted it to a ball valve to allow for the best possible flow when draining a little off the bottom. --Phil

On residential boilers I'll defer to others. With high pressure commercial or industrial boilers, it is a requirement to have a blowdown valve at the lowest point. Industrial settings are much different. Chemicals must be added, blowdown must be done on a regular basis (usually once per shift), etc. The purpose is to prevent buildup of dissolved solids and sediment. Many states require the operator have a license. Type of license varies according to boiler size in horsepower. You will often see the term "high pressure" used for boilers. Any boiler that exceeds 15 psig is considered high pressure. Ed