COLD START or MAINTAIN TEMP


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Old 12-01-07, 06:31 AM
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COLD START or MAINTAIN TEMP

i contacted peerless my boiler manufator and they told me i could use a cold start application with my indirectwater setup. or i could could set my low limit as low as it goes and the high limit should be no lower then 170 becasue boiler water returning back at 150 causes condensation. should i go with a cold start or keep the 8124? if i keep the 8124when my diff. setting is up and the boiler is mainting the low limit will my circs. still run when i call for heat in the low limit setting?\
will it bemore efficent to go with a cold start?
 
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Old 12-01-07, 07:05 AM
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Tony, I'm having deja vu ... is this Groundhog Day ? Haven't you asked this question before and gotten basically the same answer ?

Read the PDF file again for your aquastat, you need to be able to understand how that control works. If you did, you could answer your own questions!

You know the old story about 'give a man a fish, feed him for a day. Teach him to fish, feed him for life' ... I'm really trying to help you out here, not being a wise-rearend, but you need to learn to fish.
 
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Old 12-01-07, 03:22 PM
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i read it and got a few pms, from people but everyone explains it and understands it just a little differently. few people did ask me to find out if my boiler could run with a cold start and also cold start work with the indirect, i asked and they said yes i could use the cold start or the lowest setting on the 8124. im not getting much feedback on the best serup though. its costing me about 500$ month in oil i want to get the most effecientcy i possible could. is it worth me paying 150$ for a cold start aqustat? i just dont know, i would like everyones elses feedback and expierence on whats more effecnt with my setup.
as of right now i have my low limit on lowest setting and high on 180 and my diff on 10. i insulated all the pips on the boiler and put shrink wrapping on all my windows that are leaky. also chanded my 2 back doors. trying everything i could to save a buck. just so many diff opinons from local people.
 
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Old 12-01-07, 03:59 PM
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OK, here's another fish for ya, hope ya like 'em fried!

I'm gonna tell you what I would do if I were you...

I would change the aquastat to an 8148A ... as long as Peerless said you would be good to go with a cold start setup that's what I would do. If you aren't using the tankless coil there is absolutely no reason to keep the boiler warm. There are downsides though...

If your radiation wasn't/isn't designed so that the return temps get to at least 115* fairly quickly, you do run the risk of condensing in the flue passes inside the boiler... but, you still run that risk even as a warm start... even though the boiler is sitting there at 120* already, when the circ kicks on, it is going to pull cool water from the zones into the boiler.

You will probably save enough going to cold start in one month to pay for the aquastat. In fact, take a look at the 7224 ... nice electronic version... fun to push buttons on when you've got nothing else to do.

Did you pipe a bypass loop on there when you installed it ?
 
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Old 12-01-07, 04:40 PM
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Trooper beat me to it..

Cold start is great in theory, but as Trooper noted the boiler return temperature must get to 140 degrees in a reasonable period of time, and maintain that temperature for a bit, to avoid destructive condensation problems in the boiler, connector pipe, and flue.

You may need a thermic bypass valve to protect the boiler if you have a large heating load, or a system that holds a lot of water, such as cast iron baseboards or radiators.

Cold start sounds good in theory, but there is a lot more needed to insure it will work properly.

Pete

here's a good basic thesis of what can happen:
http://teca.ca/pdf/rhwha/spring-02-rh-news.pdf
 
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Old 12-01-07, 05:13 PM
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thats a good articale and also explains why past few years more and more people are installing new boilers and they do not last as long!
so you are says to go with the 8148a witch is a cold start application but now i need to install a bypass loop? i have an open spot on my speedy header to install another circulator but how do i set it up so that below 150 that circ. goes on before the boiler gets up to temputure to satisfy the rest of the house.i also have an extra supply and return that i plugged on the boiler i can make a bypass loop. the instaltion manual does not show how to install a bypass loop? im not trying to be a pain, but of all people that gave me estimates and looked at my boiler no one has gave me as much feedback as i have gotten on this fourm.... i wish you could have installed my boiler trooper!
 
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Old 12-01-07, 05:32 PM
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Tony

Bypass loops work, but it depends how many zones you have too. The best method for protect is using a Danfoss TV valve in the return. It works like a car's radiator thermostat. When the boiler is cold, all supply water is pumped back to the return. As the boiler warms up and as the return temp reaches 140, some of the return from the heating system is allowed to mix into the return. Once the return temp reaches about 160 degrees, almost all of the system return is flowing into the boiler return. Fully automatic, no fussing trying to balance a bypass loop, etc.

Pete

here is info on the Danfoss valve:

http://na.heating.danfoss.com/PCMPDF...V%20-%20DS.pdf

for the return on a oil system 140 degrees is needed.


disclaimer: I am not a pro, so any advice you take on a "free" forum usually requires some professional evaluation before being implimented! This is my opinion as a homeowner, not as a working pro in the field.
 
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Old 12-01-07, 06:00 PM
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Tony

Here's a rather simplified explanation of bypass loops. You're interested in boiler protection, not system protection.

http://www.bellgossett.com/Press/BG-insand.asp

disclaimer:
 
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Old 12-01-07, 06:05 PM
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i acutally have a tee on my supply thats plugged and can easily install a loop with the danfoss valve. but now i would have to install another circ. on that bypass loop. how do i wire that circ so it goes on before the other circs do? i have 5 zones with a taco switch relay. im gonna purchase a 8148a aqustat. and also do i need the balancing valve thats showed in the diagrams with the danfoss valve?
 
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Old 12-01-07, 06:18 PM
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Look at page two in the Danfoss PDF. You only need one circulator. It will circulate between the supply and return on boiler, until flow is permitted from the heating loop(s).

I can't advise you on whether you'd need the balancing valve or not. Sorry. I found I didn't, but that may not be the case in your situation.

Pete
 
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Old 12-01-07, 06:51 PM
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Pete, remember Tony's system looks like the test department at the Taco factory... so just how would one pipe a system bypass on that unit ? A boiler bypass would be easy, but that's not what he wants... he wants a system bypass, where the bypass line would be on the system side of the circulator. I don't think Tony can use the TV valve on his system. What he would need to accomplish that is an expensive control with a separate circ .

BTW, I don't know why B&G's info doesn't say this, but the easy way to remember what's a system bypass and what's a boiler bypass is this:

If the bypass is on the system side of the circ, it's a system bypass.

If it's on the boiler side of the circ, it's a boiler bypass.

It doesn't matter if the circ is on the supply or return, it still holds true.

Boiler bypass is for system protection.

System bypass is for boiler protection.
 
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Old 12-01-07, 06:59 PM
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Originally Posted by NJ Trooper View Post
Pete, remember Tony's system looks like the test department at the Taco factory... so just how would one pipe a system bypass on that unit ? A boiler bypass would be easy, but that's not what he wants... he wants a system bypass, where the bypass line would be on the system side of the circulator. I don't think Tony can use the TV valve on his system. What he would need to accomplish that is an expensive control with a separate circ .

BTW, I don't know why B&G's info doesn't say this, but the easy way to remember what's a system bypass and what's a boiler bypass is this:

If the bypass is on the system side of the circ, it's a system bypass.

If it's on the boiler side of the circ, it's a boiler bypass.

It doesn't matter if the circ is on the supply or return, it still holds true.

Boiler bypass is for system protection.

System bypass is for boiler protection.
Whoa Jeff, you're confusing ole Pete here..

If he has multiple circulators for mulitiple zones, then it complicates matters. That is one reason I went with Zone Valves, don't have that problem on my system. He would have to add a circulator on the boiler side of the TV as shown in first two examples in the Danfoss literature.

All four examples are for boiler protection. You can use a 160 degree valve on the supply, or a 140 degree valve on the return. I'd opt for the return side, since the differential being under 20 degrees isn't a given.


Pete
 

Last edited by radioconnection; 12-01-07 at 08:17 PM. Reason: edited for clarity
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Old 12-01-07, 08:11 PM
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As i understand i want a system bypass for boiler protection. i hve 3 or 4 extra circulator and can easly install the bypass loop with the danfoss valve. but now my qustion how do i get the circ. onn the bypass line to turnon? is it always on when boiler turns on? and also now when the boiler is up to temputure how do i stop the hot water returning into the boiler? is that what the balancing valve does?when water gets up to temp it shuts that zone off?
 
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Old 12-01-07, 08:25 PM
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On my system I have the circulators wired in parallel, but again I use zone valves and only have one circulator on the heating loop. I also went to a P/S piping arrangement to separate the boiler and heating loops, but that's another topic....

They show the example in figure 2, but I don't know how they control the circulators.

sorry..
 
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Old 12-01-07, 08:31 PM
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thanks for your help its no rush but i deff want to hook up the cold start aqustat then in a week or 2 i will draw up exactly how to setup the bypass loop and install that. thanks for everything. whats is the p s piping?
 
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Old 12-01-07, 08:38 PM
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This is a very abbreviate pictorial of my P/S piping.
P/S = primary/secondary. A google search will bring up a lot of info on it.


http://i117.photobucket.com/albums/o...PS-diagram.jpg

When you go to the cold start, you can do some measurements to monitor the return temperatures. See how long it takes the boiler to get the return temperature to at least 130 or 140 degrees, and how long it runs afterwards. You may not the bypass loop. Hard to say.

Pete
 

Last edited by radioconnection; 12-01-07 at 08:59 PM.
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Old 12-02-07, 06:51 AM
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I would like to clarify a little on N J Trooper description of bypass. Any bypass is boiler protection, and the piping determines what you want to do. It just comes down to what works best. A boiler bypass or a system bypass. Just remember when it comes to cast iron and steel boilers we want them to condense as little as possible. Manufacturers usually call for boiler bypass on these boilers with large water volume systems. Boiler bypass means the water will bypass the boiler and go back out to the system. There are advantages to this. The cool return water will blend with the hot supply and reduce the temperature of the water going to the system. This will increase the comfort level of the home and assist in saving fuel. The system water temp will circulate less than 180f most of the time. The colder it gets outdoors the hotter the system water will be. As the outdoor temp warms up the system water temperature will cool down. The larger the water volume the more the system temperature changes.
The system bypass takes hot supply water and dumps it into the return. This piping will reduce the flow rate in the system. Since radiation output is directly related to temperature and flow rate the radiation output is reduced and the system temperature still may not be hot. There is no guarantee the boiler will stop condensing with a system bypass. On a warmer day, large water volume system may return cool enough water long enough to satisfy the thermostat and not stop condensing. Gill Carlson from B&G wrote in the 50’s boiler protection is required when extremely cold water, or cool water at a high flow rate is encountered. He than went on to explain how a boiler bypass reduces flow rate in the boiler thus providing boiler protection. Bear in mind condensation occurs in the boiler if the average water temperature of the boiler is below 140f. This temperature is used as a standard but the temperature does vary between fuels. To summarize reduce flow in the boiler and increase the flow in the system. A boiler bypass will accomplish this. When installing a boiler bypass always pipe the bypass full size (1-1/4”) and never reduce the flow in the bypass, reduce the flow in the boiler. The slower water in the boiler will allow the boiler to get above the 140f. and stop condensing.
Bt the way cold start is always best if there is no domestic water coil in the boiler. Boiler protection becomes more important now!
 
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Old 12-02-07, 07:14 AM
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i dont think i can hook up a p/s piping with 5 zones? i have 5 zones in my house, i see how i could do it with 2 zones.
rbeck your saying a boiler bypass would be a better solution for boiler protection.
 
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Old 12-02-07, 10:58 AM
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You are going to get as many opinions about bypass loops as there are ... they are not easy to understand, obviously!

Which type you use depends on what you need to do.

Problem as I see it with a boiler bypass is this:

The water going into the system is going to be COOLER in general. This means that the water returning from the system is going to be even cooler than that. And that cool water returning is going to go straight into the boiler at whatever temperature it returns at. Yes, there will be less flow through the boiler, but SO WHAT ? The return water may still be cool enough to cause condensation.

I'm still down with the system bypass for boiler protection.

System bypass increases the temp of the return water, and that's the object of boiler protection.

I believe the best solution is to have a mixing valve on the return, such as the TV valve that Radio has. But, since you are zoning with circs, the problem is more difficult. You would need to dedicate a pump to the bypass, and that pump would need to be controlled by an expensive controller.
 
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Old 12-02-07, 11:56 AM
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[QUOTE=NJ

I believe the best solution is to have a mixing valve on the return, such as the TV valve that Radio has. But, since you are zoning with circs, the problem is more difficult. You would need to dedicate a pump to the bypass, and that pump would need to be controlled by an expensive controller.[/QUOTE]


Actually, you could exactly what I did. Where I have one circulator on the zones, you have several. Nothing would change there. All that wiring would stay the same. Add the TV valve protection, and have it's circulator operate with the burner. A three speed 15-58 would allow selecting the optimum flow rate for the boiler. The TV valve does all the work, there's no need for a fancy circulator with a controller and temperature sensor. The TV valve is simple, elegant and foolproof. The P/S piping allows full circulation in the heating zones when the boiler is under 140 degrees, and it gives my ODR controller full operating range without having to worry about boiler protection.

The other option is using an intelligent circulator directly between the supply and demand ports on the boiler. The circulator's sensor would monitor the return temp, and speed up as the return temps cooled. A bit overboard, and pricey, and I suspect difficult to set up...

Pete
 
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Old 12-02-07, 12:26 PM
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But what happens to the bypass circ when the TV valve closes ? Will it like being dead-headed ? And when the TV valve is bypassing, won't any running zone circs be dead-headed ?
 
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Old 12-02-07, 12:54 PM
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***NJ Trooper;1269511]But what happens to the bypass circ when the TV valve closes ? Will it like being dead-headed ?

It either shunts the flow to the bypass loop, or to the heating loop. The bypass circulator is never shunted. The total flow is always divided between those two loops.

***And when the TV valve is bypassing, won't any running zone circs be dead-headed ?

Not with the P/S piping. There is just no exchange of BTUs, but the flow is never restricted. The secondary loop is hydraulically isolated from the primary side, which is the one with the varying flow.

Pete
 
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Old 12-02-07, 01:36 PM
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Hangonaminnit... Tony ain't running p/s ... I just re-read your other post, and see that you were proposing p/s for t's system ...

OK, let me rephrase... let's say that tony used one of his spare circs to run a pumped bypass loop, and that on the return he put a TV valve. The bypass port on the TV is open until return temps come up to 140*, at which point the bypass port is pretty much closed... isn't that circ now dead-headed ?

And, until the TV starts to open the system port, won't those zone circs be d-h'd ?
 
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Old 12-02-07, 02:19 PM
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QUOTE=NJ Trooper;1269551]Hangonaminnit... Tony ain't running p/s ... I just re-read your other post, and see that you were proposing p/s for t's system ...

****OK, let me rephrase... let's say that tony used one of his spare circs to run a pumped bypass loop, and that on the return he put a TV valve. The bypass port on the TV is open until return temps come up to 140*, at which point the bypass port is pretty much closed... isn't that circ now dead-headed ?

As the bypass port closes, the return port opens. Flow is diverted to the heating loops, and returns through the return port on the TV valve. This assumes a one circulator system, with the circulator on the boiler side, and perhaps zone valves on the P/S side.

****And, until the TV starts to open the system port, won't those zone circs be d-h'd ?[/QUOTE]

That's why I like P/S piping, as shown in the Danfoss literature.
 
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Old 12-02-07, 03:21 PM
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Most manufacturers want boiler bypass with large water volume systems. I would only do a system bypass if I was doing p/s piping where the bypass piping would not affect the system flow. A TV valve works well.
 
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Old 12-02-07, 05:02 PM
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http://www.myhomeheating.com/contrac...passpiping.pdf

here is a good example of my setup but i have 5 circs for 5 zones. now could i just add this bypass loop with a 3way valve? i understand it with 1 zone just not how it would work with 5 or i amPhoto Sharing and Video Hosting at Photobucket just over thinking this.Photo Sharing and Video Hosting at PhotobucketPhoto Sharing and Video Hosting at PhotobucketI i know i have to fix the wiring and the flue i am waiting on the eletrician friend of mine to do a neat job and a weekend to fix the flue and hopefully add the bypass.
 
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Old 12-03-07, 05:30 AM
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if i add in this pipe like i drawed would that be fine for bypass loop? i lieft a link also to the website with the same setup as i have!
 
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Old 12-03-07, 08:44 AM
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Originally Posted by tony45power View Post
if i add in this pipe like i drawed would that be fine for bypass loop? i lieft a link also to the website with the same setup as i have!
I make pretty good spaghetti sauce for the spaghetti you got! Just kidding, but I couldn't resist. hehehehe
 
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Old 12-03-07, 09:27 AM
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barometric damper

That barometric damper is installed incorrectly. It should never be installed in a tee in that fashion. Also, the factory collar is advised to maintain the proper B dimension from the flue pipe. The Field instructions, and most boiler instructions, show how to do it properly.

Peter
 
 

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