Added benefit of vacuum

Fizz

Since putting system in vacuum 2yrs ago, I have not had to add water, and water in sight glass is crystal clear!

the_donut

How’s the heating bill?

PMJ

> @Fizz said:
> Since putting system in vacuum 2yrs ago, I have not had to add water, and water in sight glass is crystal clear!

The original plan never included breathing all that air in and out. I don't add any water either and my glass stays clear too.

Fizz

The heating bill is much less since I switched to gas from oil 5yrs ago, really haven't compared pre-vacuum, but my guess is it's cheaper by 5-10%. Also, the system is run in hot water mode on thermostat, so the heat is much more consistent and comfortable.

brandonf

Can that be added to any steam system?

the_donut

In theory. Depends if you want to spend the time and money to so it. 2 pipe are easier conversions than 1.

Fizz

Brandonf, my system is a Richardson, a vapor/vac, and all I did was replace the 2 air return vents with vacuum vents, and run thermostat on hot water setting.

PMJ

Like @fizz explains - this is so easy on 2 pipe systems and the benefits so large I simply don't understand why it isn't used more. Special vacuum vents aren't even required - a cheap plastic water system check valve on the dry return will do it - I have had one in service for years now holding often 80 inches water vacuum between cycles. (I am still looking for an explanation as to why the amount vacuum I reach just continues to slowly creep up without any additional effort on my part - and in 90 year old piping).

Dirt cheap, and no additional control at all required. What do you get for this little effort? Continuing significant steam delivery to the rads from the mains after the burner shuts off, minutes shaved off new steam delivery to the rads on every firing, and dramatically reduced average pressure required to deliver your steam(actually the average pressure is below atmospheric). This really does add up to something. Oh, and don't worry that deep mechanically induced vacuum is required for significant improvement - it isn't. A little negative pressure goes a very long way in this business to change the dynamics of where and how fast the steam flows.

Leonard

80 inch water is 1.5 psi , it that the max vacuum during the operating cycle? Doesn't sound like takes much vac.

Does vac pump run often? Between every boiler firing or once a day or week?

Special vac pump to tolerate water?

I assume during during heating vac goes to zero.

PMJ

80 inches water is just under 3psi.

This is natural vacuum - there is no pump.

Firings are 7-10 minutes long 3 times per hour depending on conditions. System pressure comes out of vacuum 2-3 minutes at the end of each burn with max positive header pressure of about 2 inches water.