Some 2 pipe concerns

clammy

Looking for a few thoughts on a 2 pipe vapor vacuum system thats tagged for replacement.The original boiler and piping is entact from 1932 .Here s the curve balls this is a 2 pipe possible tudor system no traps 2 pipe all convectors with what looks like the original hoffmann 76 vapor vacuum vents 1 on each main and 1 on each dry returns .The mains and dry returns are tied together below floor grade and run across the basement buried but where replaced w copper many moons ago.I watched the system run and amazingly it started in about 15 in of vacuum and the compond gauge barely showed any pressure at the end of the cycle the system pulled back down in a vacuum .The original boiler is a ideal i would possible say converted from coal to oil .The HO wants to keep it a vacuum system which means either replace the hoffmanns w new 67 which are still avaiable .The few thoughts i am pondering are is the possible need for a resourve tank (as per weil s diagrams ) being the old boiler does have quite a water content and the fact the original boilers water line is 50 1/2 the new is say 30 inch with boiler on cap blocks which leaves me to believe that this system mayalso benefit from a false water line even though the mains and returns tie together below grade .I will of course use a vapor stat even though the existing system is using a pa404 which as far as i can tell never reaches pressure being the t stat is happy way before it really starts producing pressure .I will say the steam distribution is pretty dam quick with the ends of the supply mains getting hot within a few minutes from a luke warm boiler .Still working out the edr being the excact convectors rating and cabinet enclosure sizes are hard to find so i have to return and really remeasure the cabints and convectors but from the 3 convector rating for 3 different stlye cabinets i can up with about 775 to 820 edr with out pick factor .The existing oil fired is firing 2.50 gph didn t chk pump pressure but will upon return it s running a older carlin burner .Whats the thoughts on adding a gravity resourver tanks i m a little worried about the new boiler cycling on low water due to a much lower water volume or am i just being paranoid ,the false water line may not be totally neccessary being i was planning on running the system on very low pressure max about 6 to 8 oz cut out and i realize the venting will be slow but if she still able to get into a vacuum air removal will be a moot point .I did converse w the master steam head via a phone call (thanks Frank it was totally a pleasure talking steam )this job is slated for a summer replacement .Planning on using a peerless 64-7 or 8 depending upon final edr fiqures i,ll piped w 2 3 inch risers 4 inch header connecting to 2 2 inch mains remove the cycle guard lwco and insatll a standard electronic lwco amd a manual reset lwco and of course a vaporstat and 1" wall insulation for all near boiler piping .So what s the thoughts on the resourve and fwl .Peace and good luck clammy

nicholas bonham-carter

Is there room for two smaller boilers controlled by pressure, and a two-stage thermostat? I think we are all getting tired of the 30% overrun on EDR calculations, and for vapor-vacuum systems maybe we could size the total very close to the heat loss with one boiler, or a tad more with two boilers.
When firing from cold, the thermostat could call for both boilers, and as the temperature builds, the second staged boiler would cut out. In very cold weather, the second would be cycled on and off with the pressuretrol.
Maybe the reservoir tank could be incorporated into the false water line, as a long horizontal five inch pipe, at just below the boiler water line. As it may not be needed, just leave some unions for its later installation, just in case.--NBC

clammy

i considered that but the price starts to get hi and also thought of a weil 80 series(getting to old for those peerless larger knock downs ).the plus of the 80 is higher boiler water level ,higher water content and wet based big pluses to me , downside power burner$ and not avaiable with 2 stage power burner on smaller model as far as i know and knowing that it will be noisey which is some thing they would like to get away from plus parts for any power burner is hard to aquire at least locally without a cruise or being price raped and there are very few i personally know that would go that route usually from fear of the unknown lol.If the edr was larger i would have no issue using a 2 stage power burner on a semi commerical boiler .On a side note doing 2 smaller boilers starts to get into the $ when looking at 4 inch headers vaporstats and a lead and lag rotating control aside from manual reset lwco not required but at this price why start being cheap plus a manual reset lwco is very very cheap insurance .On the other side the boiler room is not that large and i m also pricing a small hot water boiler to get away from the hw loop off the original boiler serving some fan coils in the basement and re done kitchen. if two boiler where used i would still need a resourve tank and running new stat wire for a 2 stage stat would be a issue being the basement is finished and i don t think it would cycle the boiler correctly i would much rather run them on the vaporstats pressure and with a rotating boiler control could start to get complicated . also a combustion make up air system shall be installed adding to the $ It s a manual feed system and according to the home ownwer it uses nearly no make up water unless he s perform a blow down on the lwco .It is a amazingly quite system and heats up very quick and continues dispating heat way after the burner is off due to the vacuum the boilers water level barely moves gotta love that old stuff but at 85 years old the HO is smart enough to know that it won t be replaced properly in a day and he contacted me through a supply house i deal with they throw jobs my way when a HO says nobody knows what to do with it being most look and run away, plus they never get phone calls or complaints on the refferals they give me and i buy most everything from them great for bussiness and never have to contant reps on my installs they know i cover all the bases and don t hack it in in any way shape or form i would rather not do the job then have to do crappy job cause i didnt know what i was doing or priced it wrong see way to much of that .Thanks for the input always welcomed peace and good luck clammy

clammy

As for a resourver tank i was think of a plain steel 30 gal expansion tank with a couple of weld o lets installed but wondering how it would perform under hi vacuum don t really know if there rated for that .Was hoping to add as much water volume as po$$ible say 15 gallons or so .The system mains are 2 inch and i would guess 1 being about 60 ft and the other maybe close to 80 plus .i believe it was 23 convectors or so and one wall hung roccocc in the gargage with a hoffmann orifice valve .Peace and good luck clammy

jumper

I don't think you'll ever get high vacuum. And if the tank dimples a bit,so what?

Jamie Hall

On the water line. You have three choices: raise the boiler to match the old water line, construct a false water line for the system, or deal with a raft of unpredictable water hammer and no heat problems. Take your pick. There is a remote chance you might get lucky with the lowered water line, but it's pretty remote -- better start off in the right direction.

On the reservoir tank -- I'm not sure you need it, but if you do it should be hooked up to function as essentially a wide spot in the wet returns.

EBEBRATT-Ed

I agree with @Jamie Hall , I would raise the new boiler to match the existing water line to stay out of trouble.

I have sometimes made "tanks" easily with a pc of pipe, two end caps and a couple of thread o lets if you have a welder friend. Because it's just pipe there is no ASME rating problem Also, air compressor tanks are rated for pressure, plain steel if you can find one with the right size tappings.
Sounds like a good old system that's a winner

jumper

Why not have a low water line and then run a "dry" return with loopdeeloops?

Jamie Hall

jumper said:

Why not have a low water line and then run a "dry" return with loopdeeloops?

That sometimes does work. if you find all the places which were supposed to be wet and have to stay wet, and never get water into places which were supposed to be dry and stay dry... and your pressures are always right... and the phase of the moon is right...

jumper

>>all the places which were supposed to be wet and have to stay wet, and never get water into places which were supposed to be dry and stay dry...<<

<<grin>>
isn't that what loopdeeloops are for?

Jamie Hall

jumper said:

>>all the places which were supposed to be wet and have to stay wet, and never get water into places which were supposed to be dry and stay dry...<<

<<grin>>
isn't that what loopdeeloops are for?

Yes -- and they work if you get all the places they are needed and if the pressures are kept low so that the water seals stay in place... the OP said something about 30 inches -- which gives him 1 psi or thereabouts pressure imbalance to play with.

Why risk it? Just set the boiler up on a pier.

MilanD

Looks like a great project. If you don't mind, post some pics as you go about this for us who prefer boilers over facebook and news.

clammy

Just to clear up a few water line assumptions ,the end of the main drips and the dry returns tie together below the water line in the slab so issues with steam pressurizing the return due to no loop seal is not really a issue there will be at least 25 inches of water in those loops seals and i am highly doubtful that the pressure will be more then 8 to 10 oz of pressure .On a side not the way the system is now the boiler has a 50 1/2 water line only leaving less then 24 inch between end of the dry and wet returns and there seems to be no issues at least while i watch the system operate .I will definetly post some pics at the monent still waiting to get to the home to re chk my edr and a few other lookie lous around and give em a price thats all i can do .If they go for it then all is good if not there are loads of hacks avaiable in the area that can screw it up in variety of ways but seeing theres no traps and its a vacuum systems there s always plenty of ways to knuckle head it up .The resourve tank will be talked about to the HO and water volume possible issues and low water cycling (no Auto feeder) issues that may occur ,my thoughts are a tank installed on the boiler side(as per weils diagrams and used by a wally or 2) and not the wet return side for i can t see how a tank on the hartford loop side would do much as one on the boiler side with a return and equilizer line even at only maybe 5 gal avaiable reserve that would give me maybe a additinal 6 to 8 minutes of steam aside from what i can get cycle wise out of the boiler according to the manafactures info on steam rated gpm which is a little below .50 gpm .Should know weather its a go by after tax day lol thanks for all the input peace and good luck clammy

JUGHNE

This is a reservoir tank that has the HF loop entering the end of the tank. The tank has 2 bottom outlets connected to the 2 inlets of the boiler. The equalizer from the header is connected to the top of the tank. It takes 95 gallons to fill this 525,000 BTU system. Never runs out of water while steaming even after a deep 24 hour setback.

jumper

There are ways to deal with waterline too low. But too high? Then come receivers & condensate pumps & more tanks. At least that's what I remember.