Should I cold start? And wiring options

Reply

  #1  
Old 12-18-18, 02:26 AM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Should I cold start? And wiring options

Hello everyone, I am a long time lurker who is new to the forum. Right now I have a thermodynamic S series steel oil fired boiler with 2 circulators piped to the return side and old line voltage thefmostats. The boiler is in good overall condition and I plan to update the controls and piping to modernize it. I read a book called ďPumping AwayĒ which greatly helped me understand the fundamentals of a hydronic system. Im going to start by updating my controls. I have a hydrolevel 3250 plus aquastat and a taco SR502-4 switching relay waiting to be installed. I also pulled new thermostat wire and am installing smart thermostats. I will no longer be using the tankless coil for my domestic hot water. Iím confused about whether or not I should cold start it or leave it as a warm start boiler. If I do leave it as a warm start I know I could turn the low limit down a lot further than it currently is because i will no longer be utilizing the tankless coil. I have searched all over and I am still confused on what to do. Whatever I decide To do will change how I wire the controls. Thats a whole other bag of worms. Lol! Any help would be greatly appreciated. Iím pretty new to oil fired hydronic systems.
 
Sponsored Links
  #2  
Old 12-18-18, 09:01 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 47,590
Welcome to the forums.

Thread moved to the boiler forum.
 
  #3  
Old 12-18-18, 09:22 AM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Thanks for moving the thread. I appoligize. I didnít realize I put it in the furnace group. I called hydrolevel today for some advice. Guy recommended to keep the boiler warm start and turn the low limit down to 120 degrees. Also told me to connect the taco end switch (XX) to the hydrolevel (TT). Only thing that is confusing is that the hydrolevel instructions say that setup is for a single circulator. Then again I wont be running the circulators off of the hydrolevel. They will be controlled by the taco. Idk why I am so confused about this...
 
  #4  
Old 12-18-18, 09:24 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 47,590
No problem. The boiler guys will be by. My specialty is furnaces.
 
  #5  
Old 12-18-18, 10:11 AM
Member
Join Date: Nov 2011
Location: USA
Posts: 395
I'm not a big fan of converting conventional warm-start oil-fired burners into cold-start unless there is some kind of "bypass piping" involved. It doesn't seem to me that the benefits would outweigh the drawbacks. A very good article on the subject can be found HERE.

I took a quick glance at a Thermodynamic S series manual and I noticed that the manufacturer mentions protecting the boiler by maintaining warm water even in cases where there is neither an internal HW coil nor an indirect HW tank to support (page 8) :
If the an indirect hot water heater is not used, the low limit may be set between 120įF and 140įF to provide protection against condensation in the boiler. The settings are nominal and many be adjusted for the particular installation conditions.
Just my two cents.
 
  #6  
Old 12-18-18, 11:25 AM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
After some more research and reading your reply I think Im going to keep it a warm start and set the low limit around 130. Maybe when I re-pipe the circulators to the supply side I will think about making it a primary/secondary system. Now I am just confused on the wiring. According to the hydrolevel instructions ZC/ZR should be connected to ZC/ZR on the taco SR502-4 switching relay, but then I read conflicting information and was told by tech support to use TT/XX connections between the two. Im essentially looking to maintain a lower boiler tamp and fire the boiler up to the high limit on any call for heat. Once I get that figured out I can screw around with the hydrolevel economy settings to find what works best.
 
  #7  
Old 12-18-18, 01:32 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
H,
If you are no longer using your tankless coil you do not need to use the ZC & ZR terminals.

The purpose of these terminals is with a warm start boiler so that when the boiler water temp drops below the LO LIMIT the heating pumps shut off and give the domestic hot water priority.

When the boiler temp climbs back up above the LO LIMIT the pumps reactivate to deliver heat again.

Since you are doing away with your coil you can eliminate wiring those terminals.

You can still keep your boiler warm start, the only difference will be the heating pumps will continue to run as long as there is a call for heat, not worrying about the hot water coil.

If you google ZC & ZR terminals you may get some sight with more info or better explanation.
ZC is zone control and ZR is zone relay.

Hope this helps a little.
 
  #8  
Old 12-18-18, 01:53 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
so if I wire XX on the taco relay to TT on the aquastat, I will still have Low limit control to maintain some heat in the boiler? On a call for heat the circulator will start and burner will fire to hi limit? Or will the burner only fire if the temp drops below the low limit?
 
  #9  
Old 12-18-18, 04:23 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
H,
I believe so, as long as you leave the priority switch on the Taco to OFF you should have all your functions.
 
  #10  
Old 12-18-18, 04:28 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Awesome. I guess the only way to really tell wouldbe to try it out. Thanks for your help guys. If anyone wants to chime in with any more input please do. I have been trying to start this project for some time. Of course I am the idiot who puts it off until winter 😂
 
  #11  
Old 12-18-18, 05:39 PM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,815
A couple of more thoughts on warm-start vs. cold-start boilers.

A cold-start boiler, and its flues, experience more frequent and deeper thermal expansion/contraction cycles for metal boiler parts and flues. Some have theorized that can lead to leaks when converting from warm-start to cold-start. I don't know, but it sounds plausible. My warm-start, hot-water boiler is 60 years old and running like a champ.

A supposed advantage of cold-start is that it reduces the stand-by heat losses when there is not a heat call. I calculated the stand-by heat loss for my boiler - it is peanuts, dollar-wise, over a year. (I do shut my boiler down during summer months - I have a separate stand-alone natural gas water heater. But either way, I think standby-loss would be peanuts, at least for natural gas.)
 
  #12  
Old 12-18-18, 06:38 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Yes I agree. My primary reason for doing all this is to get rid of the tankless coil and make the system perform better. Right now its basically just controlled with line voltage thermostats and An old aquastad. I figure not using the tankless coil, plus the effeciency features of the hydrolevel, and a lower standby temp will save some significant amounts of oil. My house has solar which produces more electric than I use so I will be heating domestic water with a heat pump water heater. The boiler on standby also keeps the unfinished basement somewhat warm so its not a total loss.
 
  #13  
Old 01-06-19, 08:13 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Hello everyone. Just wanted to say thanks for the help! Been very busy, but the install is done. Heat pump water heater installed, no more tankless coil, taco switching relay, and hydrostat installed. All systems up and running great!!
 
  #14  
Old 01-07-19, 10:10 AM
Member
Join Date: Apr 2014
Location: us
Posts: 489
An alternative to cold start is to use Hydrolevel with Outdoor Sensor kit. It will adjust boiler water temp to what is needed based on outside temp cutting fuels costs. That is more effective that build in learning system on Hydrolevels.

https://www.supplyhouse.com/Hydrolev...oor-Sensor-Kit
 
  #15  
Old 01-07-19, 12:40 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
Good to hear everything is working. Thanks for the update.
 
  #16  
Old 01-10-19, 08:49 AM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
An alternative to cold start is to use Hydrolevel with Outdoor Sensor kit. It will adjust boiler water temp to what is needed based on outside temp cutting fuels costs. That is more effective that build in learning system on Hydrolevels.
playing with the thermal targeting feature on the hydrolevel and Iím not sure if its a good idea to use it on this boiler. Last few days have been fairly warm so the heat hasnít been running too much. That may have something to do with it. The thermal targeting has adjusted the target temp to 145 on occasions. If the boiler is sitting at about 140 and both zones call at the same time, the boiler will fire but the temp will drop fairly quickly. I have seen the water temp drop to 114 before starting to come back up. Then the boiler will run for 5-7 minutes to hit the high limit which is currently set at 185. This boiler is way oversized for my house. Im thinking I might have better results turning the thermal targeting off, setting high limit at 190, and a wide differential of 30 degrees (this is the max for the hydrolevel). Wish the boiler would run for longer periods. The lowest recommended nozzle is a 1.0 so Iím not sure if its a good idea to step down to a .85
 
  #17  
Old 01-10-19, 12:20 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
What model or size boiler do you have, (S 85, S 100 etc.). What burner do you have, (Beckett, Carlin, Riello). There can be more to dropping a nozzle size that just doing it. Adjustments must be made and sometimes the burner head must be changed.

That being said if your firing rate is 1.00 then your nozzle size is most likely or should be .75 unless somebody has changed it. Your firing rate of 1.00 from a .75 nozzle comes from the pump pressure of 140 PSI instead of the standard pump pressure of 100 PSI.

My point is if somebody has worked on your boiler and saw the firing rate and didn't do there homework you may have the wrong nozzle in there and are over firing your boiler. Just saying it's a possibility. If you have an S100 boiler you should have a .75 in there already.

As far as your control settings go I would do just what you're thinking and shut off the T.T. and play with your differential which is there to mainly help with a short cycling problem. Just beware, the lower the boiler temp the less heat you will get from the emitters.

Below is a sight you may find helpful with info on your boiler. It will show you what your firing rates should be.

S SERIES

Hope this helps a little.
 
  #18  
Old 01-10-19, 12:41 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Thanks for that info. To be honest with you I really donít know which model I have. There is no tag on the boiler itself. The only decal on the boiler itself is the service tag for initial adjustments where its lists the specs for the S125, S135, and S150. I took a look at the website and these models are marked with an asterik that says ďblended firing rateĒ. That leads me to believe that those 3 boiler model numbers may be the same, but are defined by the nozzle size and settings. Looking at the specs of all the models from S85-S150, they are all the same size. I dont inow how to identify which one I have. A pretty reputable boiler guy changed my nozzle to a 1.0 and said that was the smallest that should be in my boiler. That 1.0 nozzle replaced a .85 that was put in by an unknown person before I bought the house. Looking at the specs, if I do have a S125, that has a net rating of 130,000 btuís which is way oversized for my 2200 square foot home located in Long Island NY. I wish I had a clue how old this boiler was. I was toyong with the idea of doing a heat calc and replacing the boiler with a properly sized unit. Just hard swallowing that pill to pay for something thats working ok.
 
  #19  
Old 01-10-19, 01:15 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
Just from increasing your nozzle size from .85 to 1.00 you increased your BTU output by 21,000 BTU's which in your case in very counter productive. If you were oversized with the .85 the new nozzle made it worse.

How did the tech know what nozzle you needed if there are no model numbers on there. That's the only way to tell the boiler size.

You must have numbers somewhere, even if you don't understand what they mean. Are pics of the boiler possible. Look to see if there is a removable panel somewhere but with boilers there is usually a tag on the casing. Do you have the book. How did you know it was a Thermo-Dynamics boiler.

Remember the oil pump pressure on your boiler came factory set at 140 PSI which increases the oil GPH.

Pics would be very helpful.
 
  #20  
Old 01-10-19, 01:29 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
These are the only identifying tags on the boiler. The serial number box is empty. I donít have any paperwork on this boiler. The tag lists the specs for S125, S135, S150.
 
Attached Images   
  #21  
Old 01-10-19, 01:35 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Im trying to figure out how to upload better quality pics. They look great on my phone until i upload them
 
  #22  
Old 01-12-19, 06:32 AM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
So I contacted thermodynamics and sent them the pics. They said based on that service tag the boiler is a S125/S150 series and the size of the nozzle determines how its referred to. There is a 1.0 nozzle in there now, so that makes it a S125 with a 130k btu rating. As soon as I can I think I am going to calculate a heat loss in my home. This boiler is probably pretty oversized. May be time for me to start thinking about a nice summer project of putting a new boiler in. This one is working but Iím estimating it to be 20+ years old.
 
  #23  
Old 01-12-19, 10:29 AM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
Did you ask them about dropping down to a .85 to lower your net rating. As long as your satisfied with the way this boiler works it would be a lot of needless expense to replace just for a smaller unit.

Although age deserves some consideration it's not the end of the world.

Just my thoughts.
 
  #24  
Old 01-12-19, 12:53 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
I ran it past them and they said 1.0 is the smallest recommended nozzle. There was a .85 in there when I bought the house and my boiler guy did catch that a 1.0 was the smallest recommended and changed it. It is an old boiler and who knows how long it has been short cycling. It was plumbed rather lousy. If anything I plan on at least redoing the circs and moving them to the supply side and adding a spirovent. If I did replace it it would just be for good measure so I can be worry free for the next 20 years. Believe it or not I actually enjoy wirking on this stuff. I was completely clueless when I purchased the home and knew nothing about hot water oil fired systems. After updating the controls last week I currently have the hydrolevel set at 180 high limit, 140 low limit, 20 degree differential, thermal targeting feature off, and purge function active. Im on the fence with the purge function. With both zones calling. It will purge down to about 135 degrees before the boiler fires and brings it up to the high limit. Cycle times seem longer now. About 4-8 minutes. Its probably not ideal, but better than what it was doing. Do you think maybe I should turn the purge function off and raise differential to 30 degrees?
 
  #25  
Old 01-12-19, 01:33 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
I'm not familiar with the purge function. I'll see what it's purpose is.
As far as the nozzle they are probably being cautious about the smaller nozzle not delivering enough heat and possible draft and chimney condensation problems.

I still don't fully understand their reason because all the different BTU sizes have the same dimensions except if you look at the weight of each size. It increases but with all the same dimensions I don't know how. I called myself but the rep was on another call but I will call back out of curiosity.

Where you are finding this interesting you could try lowering the nozzle and make the adjustments and watch to see what happens. If you start to get condensation or low temp exhaust you can just reinstall the 1.00.

Just for info purposes my boiler calls for a .85. I'm running a .65 and raised the pump pressure up for better atomization and it's been 2 years with no problems.

Just a thought.
 
  #26  
Old 01-12-19, 01:41 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
I thought the same thing. First thing I did was look at the dimensions of each boiler. The only difference is the water capacity. That kind of has me baffled. LOL next tune up maybe I will mention it to my boiler guy. I donít see chimney draft as an issue. Its got about 30 ft of 6Ē stainless steel liner in a clay flu chimney. Wish I could do the maitanance and tune up myself. I have toyed with the idea of purchasing a combustion analyzer but I think it may not be worth it. I carry a contract with my boiler guy in case anything goes wrong. I work long hours and Iím often far away from home. Its nice knowing that if the heat goes out I can call a professional to come get the house back up and running with the wife and infant home without me.
 
  #27  
Old 01-12-19, 01:48 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
Just saw on the thermodynamics website that the S110 which is listed with the .85 nozzle has the same water capacity as the SS125-S150. I dont know.... I see a new weil mclain boiler in my near future just for piece of mind.
 
  #28  
Old 01-12-19, 02:24 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
Good boilers. That's what I have.
The last couple I put in were Slantfin and they were very nice and a lot cheaper that W.M. They cam a long way. W.M. is a good boiler but got a little out hand with there pricing and also have a 7" smoke pipe which is standard for their boilers and could become a problem if you have an 8 x8 chimney that needs relining because a 7" liner will not fit. Had to find different boilers a couple times for that reason.

Just in case it would ever be an issue, thought I'd mention it. Sight below to see your options.

https://www.supplyhouse.com/Oil-Boilers-1737000
 
  #29  
Old 01-12-19, 02:27 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
I have a 6Ē liner now that would work for the weil mclain. If I redo the boiler I would want to pipe it with a promary/secondary loop with an electronic valve that adjusts based on supply/return temps. I havenít research enough yet to figure out the best way to do that.
 
  #30  
Old 01-12-19, 02:37 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
How is a 6" line going to accept a 7" vent pipe. Liner must at least be as large as vent.

I did call W.M. at one point and up to a certain size boiler and I don't remember what size you can go from 7-6 without a problem but other than that you can not choke down the exhaust pipe. They are sized for the boiler design.
 
  #31  
Old 01-12-19, 02:42 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
I just assumed you can downsizee to a 6 inch liner going up the chimney. I have done a bunch of wood stoves (for myself and friends). Generally you have a problem if you are using the clay flu. My liner is 25+ ft long. I donít see not enough draft being an issue. Idk though. Im not a oil fired boiler professional. I appreciate any input. My specialty is cars.
 
  #32  
Old 01-12-19, 02:52 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,381
What happens with boilers is if you choke the exhaust down so it does move enough heat fast enough from the boiler you get back draft in the unit which is not good for the chamber or assembly.

If you are set on W.M. I would call them and make sure it will work before installing it.
Just a suggestion.

https://www.weil-mclain.com/products/boilers
 
  #33  
Old 01-12-19, 03:10 PM
Member
Join Date: Oct 2008
Location: USA
Posts: 2,815
If you have a fire-clay chimney liner, you shouldn't also need a stainless steel liner - unless the clay liner is somehow damaged. A vitrified-clay liner should last indefinitely. I have four of them (for three wood-burning fireplaces and a hot-water boiler), and after nearly 70 years, they are fine. Periodic inspection is a good idea.
 
  #34  
Old 01-12-19, 03:23 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
If you have a fire-clay chimney liner, you shouldn't also need a stainless steel liner - unless the clay liner is somehow damaged. A vitrified-clay liner should last indefinitely. I have four of them (for three wood-burning fireplaces and a hot-water boiler), and after nearly 70 years, they are fine. Periodic inspection is a good idea.
every wood stove I have done I have lined the chimney with a stainless liner. Around here fireplace clay flu is generally 12x12 which is way too big. My neighbor runs his wood stove into a12x12 clay flu and had a fire last year. Its impossible to clean the creosote completely without a liner. In my opinion a liner is superior to any clay flu. When I did my wood stove I even insulated the liner. The draft is amazingng. Sounds like a jet engine when you open the door and the stove runs great.
 
  #35  
Old 01-12-19, 03:26 PM
Member
Thread Starter
Join Date: Dec 2018
Location: USA
Posts: 45
I should also mention that a liner makes a difference if chimney is interior or exterior. Most chimneys around me are exterior.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes