New PB105 setup

[Wayne64SS]

I think I finally have my head wrapped around this whole "proper independent control of 2 boilers" thing. My current setup is a PB105 and old Oiler plumbed in series. No DHW, no heat storage, just super simple and yet configured incorrectly.

I do not currently have independent control of either boiler. The only aquastat in the system is located in the oiler. Currently there is NO balancing / tempering valves installed at all.

Here is my proposed solution, and a few questions....

1)Will this setup allow me to run on JUST oil?
2)Will this setup allow me to run on Pellets with oil backup?
3)I am hoping that the "Boiler Selector / Control Relay" will allow me to switch from pellet to oil with a switch?
4)Does anyone have a part number for such a device?
5)Where can I buy a Termovar 4440A-3?

You think this will work?!??! I'm ready to start order parts and cutting pipes

Thanks in advance!!

 

[vvvv]

heating the oil boiler will result in heatloss

 

[Wayne64SS]

I am aware of that, however my oil boiler is not a cold start capable boiler, and as such it needs to have heat in it. the temp drop across the boiler is very small when measured from inlet to outlet with a heat gun.

 

[Sting]

I think I finally have my head wrapped around this whole "proper independent control of 2 boilers" thing. My current setup is a PB105 and old Oiler plumbed in series. No DHW, no heat storage, just super simple and yet configured incorrectly.

I do not currently have independent control of either boiler. The only aquastat in the system is located in the oiler. Currently there is NO balancing / tempering valves installed at all.

Here is my proposed solution, and a few questions....

1)Will this setup allow me to run on JUST oil?

no -- well not without a huge heat loos in the cold PB105

2)Will this setup allow me to run on Pellets with oil backup?

yes again the OB will be a heat loss up the stack -- do you have an Efical on that stack?

3)I am hoping that the "Boiler Selector / Control Relay" will allow me to switch from pellet to oil with a switch?
4)Does anyone have a part number for such a device?

Wire in a separate thermostat for that one zone your diagram shows for the PB105 - Then simply set the existing stat at say ??? 50 ish and when the pb fails and the house temp drops to 50 the OB will fire and pick up the load.

5)Where can I buy a Termovar 4440A-3?

Why would you want such a contraption in a series setup? Think like the water! Either that expansion tank is in the wrong place or the pump is.

Kind Regards
Sting

 

[Wayne64SS]

Uuugh. Im trying not to redo what is currently down there, only trying to get the oiler to stop running when its not needed. The termovar is to stop the shocking of thepellet boiler. Currently under load it wont get over 140deg.

 

[Sting]

OK -- THATS NEW INFORMATION

So two things -- the contraption is in the wrong place to do what you want it to and second you are (likely) circulating too fast thru the PB105 and the water is not able to pick up the energy available -- so the boiler is running cold

guessing here -- need more info - but if I am correct you need a valve on the supply side of that circulator and you need to use it to choke the flow so the Harmon has a chance to do its job -- and keep up to the load that possibly is too big ????????

 

[Delta-T]

am I to understand that there is not auqastat installed in the PB105? If this is the case, you have the aquastat from the oiler linked to both the oiler and the PB105? If you intend to use the oiler as primary and the PB as backup then I think they are installed in reverse, mind you, I'm no plumber. Without an aquastat in the PB how does it know when to work? the unit heats to satisfy the temps on the CB as measured by the aquastat....so I think you'd need that. If you're running series, then you've somehow made this way too complex IMO. Just set the unit up like normal and set the temp on the standby unit lower than the primary unit. If you want to use the PB as backup then......um....I think you'd want the PB after the oiler in the setup. I'm not sure how effective you can have the standby in the front position for that type of operation.

 

[Bill Bennion]

I have a PB 105 with a simple series setup with a Weil-Mclain oil boiler, I have disabled the low temp since the dhw is no longer used. I am adding a relay that will pickup the 120v from the combustion fan on the PB using NC contacts to control the TT terminals on the oil burner.m I am also installing a Ranco ETC to pick up the stack temp as a secondary control for the oil burner.

 

[Bill Bennion]

Here is a pic of my system

 

[Wayne64SS]

OK -- THATS NEW INFORMATION

So two things -- the contraption is in the wrong place to do what you want it to and second you are (likely) circulating too fast thru the PB105 and the water is not able to pick up the energy available -- so the boiler is running cold

guessing here -- need more info - but if I am correct you need a valve on the supply side of that circulator and you need to use it to choke the flow so the Harmon has a chance to do its job -- and keep up to the load that possibly is too big ????????

hmmm, what info do you need / want? I'll try and provide anything and everything i can, I really appreciate the help. I don't see why the load would be too big for the PB-105, if my old boiler handles it no problem. Let me try explaining a little better.....

I am in series config now, PB main, oiler backup. Piping goes out of PB, into oiler, out of oiler, into radiators, into PB. Only circ is on the return from the radiators just before the PB.

When the demand call comes in it goes to the aquastat on the oiler. This kicks the only circ on which is located on the return to the PB. (the PB has built in aquastat and controls for itself not a circ) The PB is at max temp (180) at this point in time. As the water circulates the cold return water comes back in from the radiators into the PB and drops the PB temp in a hurry. PB will fall to 140 and maintain there abouts. The circ will NEVER kick off during a demand call because it is located on the oiler and it's min is disabled because i have to have that all the way down for the oiler not to run all the time. The max temp on the oiler is 135ish.

The way it used to function (before i bought the PB) is that the max on the oiler was 185, min was 165. Demand call came in, oiler kicked on. When the oiler dropped to min temp the circ kicked off till the boiler caught up, then would kick back on if the demand was still there. This worked great for heating the house, as the old cast iron radiators were always around 170-180deg.

Currently my radiators won't get to 140.

IMO I need to have it set up so the circ will run till the PB hits say a low of 160. then the circ should kick off, but not transfer control to the oiler. PB catches back up, circ kicks on again etc etc. However when the system sees an extreme low temp of say 135, the oiler should then take over and function the same way it used to.

What components do I need to install to make this happen?
I was told it's a VERY good idea to have a tempering valve on the return to the PB so I don't shock it.

My house is only 1100 square feet of ranch. older windows and insulation. My oiler is an OLD "CB by Burnham".

I appreciate everyone's time, and I'd love to get this resolved so I can go back to having a warm house.

 

[Sting]

Here is a pic of my system

The correct location of the expansion tank is at the point of zero pressure change in the system. This is usually near the air separator.

Tanks in two locations will "absorb" pressure at there respective points causing pressure fluctuations in the system

 

[Wayne64SS]

Sting,

I think I put my tempering valve in the wrong place in the pic.... in the pic it should connect the pipe with the expansion tank with the pipe with the circ right???

 

[Bill Bennion]

Here is a pic of my system

The correct location of the expansion tank is at the point of zero pressure change in the system. This is usually near the air separator.

Tanks in two locations will "absorb" pressure at there respective points causing pressure fluctuations in the system

Pressure at both boilers rus the same no fluctuations

 

[Sting]

Sting,

I think I put my tempering valve in the wrong place in the pic.... in the pic it should connect the pipe with the expansion tank with the pipe with the circ right???

The Pump should be pumping away from the expansion tank -- the point of zero pressure change.

Lets Start here with a Primer on Hydronics

http://www.bellgossett.com/literature/files/1195.pdf

Please read, read, read:

(broken link removed to http://www.radiantandhydronics.com/Articles/Glitch_and_Fix)

 

[Sting]

Like I wrote in another thread

I miss all the great links I had buried in that other web site to help on little issues like this

 

[Wayne64SS]

Read the BellGossett link, thanks for that. I know a little bit more about how some of this stuff works. I will check the next one tomorrow.

Does post #9 make any sense to you at all??

 

[Sting]

yes - did my quote?

 

[Wayne64SS]

you quoted post #9???

 

[Wayne64SS]

Sting,

I think I put my tempering valve in the wrong place in the pic.... in the pic it should connect the pipe with the expansion tank with the pipe with the circ right???

The Pump should be pumping away from the expansion tank -- the point of zero pressure change.

Lets Start here with a Primer on Hydronics

http://www.bellgossett.com/literature/files/1195.pdf

Please read, read, read:

(broken link removed to http://www.radiantandhydronics.com/Articles/Glitch_and_Fix)

Hmmm I think I get it about the circ now. Am I correct saying it should be in the line after the expansion tank, and before the load?

Are you saying I'm not shocking the PB at all? I don't need any kind of mixing or tempering valve in the system??

 

[Delta-T]

What have you set for the Min and max temps on the PB? Are you running the outside air sensor? and what is your feed adjuster set to? The PB should have no problems generating the temps you want with just the 1100 sq ft to move it to. I've seen it do 3X that space with no difficulties, in an old place with bad windows and such. I dont claim to know how your setup will affect the operation, but I'm pretty familiar with the why's and how's of the PB.

 

[Wayne64SS]

Min is set at like 160, max is up all the way at 185. I tried raising and lowering the min last year to see if it would help. My feed adjuster is up at 6, and I have no outside air sensor.

 

[Delta-T]

hmmm, I'd turn the feed adjuster down to 4-4.5 ish. When the ESP reads really high temps it tells the stove to slow down, by having the feeder at 6 you tel the unit it is allowed to feed at maximum as the temp differential widens between what you've requested (via control board) and what the machine is measuring (via Aquastat). As this differential increases, the amount of pellets entering the burnpot can drive the combustion temp up very fast, and the heat transfer to the water is not quite as fast, convincing the unit it is burning too hot and then slowing down to an acceptable level, all the while your water is not getting as hot as you'd like. Are you only using the combined temp/pressure guage on the PB to check its operating temps? I've seen those things be off by a significant amount before. I've also seen when there is a bit of air in the PB the aquastat gets temp spikes and thinks its at a higher temp than it really is. Using the outside air temp sensor will tell the unit to default to a higher min temp as the outside temp drops. this may help you out, I can't see how it would hurt either way. Any chance you've had a service tech hook up the DDM module to the PB control board to see what the unit "thinks" its doing?

 

[Wayne64SS]

Does the same thing with the feed at 4 41/2. i literally tried every setting on the PB itself.

 

[Delta-T]

thats wacky. that machine is a beast and should be able to heat your 1100 sq + an in ground pool. Do you also have a visual temp gauge on your oiler to help you confirm the temp at the PB?

 

[Wayne64SS]

yes, and the temp guage on the pb is usually around 20deg off from actual. actual will be 130-140 under load, pb shows 120-125. Already had guage replaced, same.