steam vs vapor system

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1850836#Comment_1850836

Try Dwyer. They have quite a variety (to put it mildly) and there are a few which might suit. They aren't cheap…

ethicalpaul

Dwyer low pressure switches are cheaper than vaporstats and even cheaper than pressuretrols, even when new (but I buy them NOS on ebay)

Steamhead

We tried a Dwyer once a long time ago and it didn't hold up well. So we went back to Vaporstats.

Jamie Hall

The microswitch Vapourstats do have a reputation for being out of calibration. However. There are two fixes for that. With care and a very reliable low pressure gauge and a suitable rig they can be recalibrated (but the procedure is NOT the same as a Pressuretrol!) However there is another approach which will appall the purists. Mounted with a good low pressure gauge — which they should be — just alter the set points on the scale so that it switches when you want it to.

The mercury switch variety is set exactly where you want it to be simply by adjusting the level.

Both flavours are very precise — that is ,they will cut out and cut in at pretty close to the same place every time. Which is what you want.

And, if you don't overpressure them (they'll take a lot but it can be done) they will last forever.

mattmia2

You could make a monometer out of tubing that is more or less incapable of being inaccurate to do your calibration.

WilliamGwiazdowski

Had a poke inside of the pressuretrol this evening and the differential is set at 1. I'm facing kind of a double edged sword. First of all the system works great heats the house nicely but at the expense of substantial fuel bill. Do I mess around with it to try to reduce the fuel bill or do I just leave it alone?

delcrossv

Don't know if you'd get noticeable fuel economies from a pressuretrol.

Insulate and install storm windows if that's your concern.

ethicalpaul

it won’t affect the heating bill that much. The BTUs are going into your house regardless. But I don’t like the pressure so my Dwyer, which has never once come close to giving me any trouble, handles it

WilliamGwiazdowski

So I think for the moment I will just leave everything as is. In the next couple of months I am going to be installing an electric high efficiency hybrid hot water tank and completely abandoning the domestic coil in the boiler though.

mattmia2

As long as the pressure isn't high enough that it is causing issues like banging or keeping some parts from heating and the pressure isn't like 4psig, reducing the pressure with a pressuretrol or vaporstat setting is only going to have negligible savings, it will transfer a little more heat to the steam at lower pressures but it is only going to be a percent or 2 at most.

What could save something more on the order of 5%-10% is sizing the boiler so it never or very rarely cycles off on pressure. every time the boiler cycles off and cools to reduce pressure then begins heating again there is some amount of time the boiler is steaming very little to not at all and while that is happening you still have losses to the basement from the boiler itself and losses up the vent (a vent damper helps some) but you are putting very little heat in to the system. some of the losses to the basement makes it in to the house but some leaks out around the sill and drafts up trough walls and such.

WilliamGwiazdowski

So I think I'm going to leave well enough alone because all the radiators heat very well. I do have two radiators which are shut off which are in rooms that never get used. I think I only have 269 sqft of radiators in use and the boiler outputs 379 sqft

delcrossv

Don't mess with success.

WilliamGwiazdowski

Exactly. However I do need to do some maintenance to the boiler over the summer when it's not running. Needs a new combustion chamber and then I want to have somebody come in and do a combustion analysis and efficiency test the last time that was done was 2012

delcrossv

https://forum.heatinghelp.com/discussion/comment/1850857#Comment_1850857

Hmm. Two of them and a toggle relay would duplicate a vaporstat. Hi limit closes-toggle off, low limit opens-toggle on.

jumper

Ideally air is expelled and prevented from getting back in. Some vapor systems had devices and piping to attempt that ideal. Common steam heat inhales air which has to be re-expelled.

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1851498#Comment_1851498

The problem with that ideal is that it is exceedingly difficult to make a seal which works over time against even a relatively low vacuum (how many threads are there on overhead oil lines which lose prime?). And a really truly tight steam system can develop a startlingly high vacuum when the boiler cools down — 20 inches of mercury would be a conservative value. The vapor pressure of water at room temperature is around 3 psia…