Gravity conversion protecting boiler

BillyP

I am replacing a boiler on an old gravity system.  I am using a non condensing boiler.  I usually pipe the boiler P/S on this type of system to protect the boiler.  The last one that I did, I was talking to someone at Burnham's technical service on the phone and he told me that Primary/ secondary will not protect the boiler and that I should use some type of bypass valve.  Is he talking about a four way mixing valve or something different?  I looked on Taco's website and couldn't find anything.  Who makes one?  Also was the Burnham guy correct in saying that piping it Primary/ Secondary does not protect the boiler?  I was always under the impression that this was a good way to protect the boiler on a gravity conversion.  Thanks for any help. 

Paul48

He's

right, in that P/S alone does not guarranty boiler protection.If your system pump is matched with the boiler pump, the only thing you have done is make sure you have constant circulation through the boiler.Beyond that, Delta-t circulators, 3-way, 4-way or Taco "I" series with outdoor reset valves, or even an ESBE thermic valve will ensure boiler protection.

BillyP

where can I find piping diagrams

Where can I find piping diagrams for these setups?

icesailor

Mixers:

Try this one. I have had great luck with it. You actually make it P/S with a circulator on the primary and secondary side.  The primary side (boiler) can run at whatever you decide as a minimum) and on ODR, will run the system at whatever the ODR decides with you controlling the re-set ratio. If you choose to use an indirect, you don't need to get into any quirky control strategies. You can set the high limit at what you want, and the high limit on the boiler will stay there, whether a call for heat or a DHW call. But the secondary/system will be run by the valve and the ODR. The valve comes with all the sensors you need.



http://www.taco-hvac.com/en/products/i%20Series%3Csup%3E%26reg%3B%3C/sup%3E%20Mixing%20Valves/products.html?current_category=184

Mark Eatherton

I vote for the ESBE THermic...

I've seen the insides of boilers that were allegedly protected by the other means, and there was some substantial signs of condensation occurring in those apps. When employing the thermic, I've never seen ANY signs of condensation. One moving part, no wiring, great product.



Google ESBE Thermic and it will take you to a Danfoss web site for piping information etc.



ME

BillyP

ESBE Thermic

Ok.  I found the piping diagram.  I don't understand it though.  Whatg is the second bypass for?  Also If I am installing an indirect, where would that tie in? This is the diagram I am looking at:

http://na.heating.danfoss.com/PCMPDF/ESBE_TV_instructions.pdf

icesailor

Asking?

If you're asking me, that's not a 4-way.

I personally think the 4-way is an easier valve to install. There are no by-passes. The boiler I put this one on had a circulator on the indirect and one on the system. The only thing I did was to connect the boiler/system loop and make it the boiler loop by connecting the two ends together. Installing two closely spaced tees in the manner recommended by Taco in the instructions, and connecting one side of the 4-way th the boiler side and the system side with the other with a new circulator. I connected the two circulators together so they run together.

The first picture is before, the second one is after.

I did not install this boiler and piping. I only added the 4-way. And because of my dyxlesia, and in spite of marking every part of the valve with a magic marker, it is installed 180 degrees off. It has been rotated the 180 degrees.

Mark Eatherton

Either way...

The bypass is actually where the valve receives its hot water from to raise the return water temperature above the condensing point.



As for DHW, if you want to use a pumped priority, you'd put a check valve on the space heating pump, and then tie the DHW return in between the pump and the boiler, and make certain the DHW pump is also checked. The DHW supply would be a branch off of the boiler supply.



The other way would be to utilize zone valves, and using a limited priority controller, set the DHW zone valve up like any other zone valve controlled zone.



Personally, I prefer the use of a pumped priority because it recovers so fast, and the flow rate is not limited by the zone control valve.



Don't get me wrong, other systems CAN be set up to provide good protection (4 way, or VSI), but I try and keep things simple, and the ESBE does in fact do that.



One word of caution. If you typically set your purge up so that it flows through the boiler, you will have to incorporate a complete ESBE bypass in order to purge. The alternative is to put the purge before the ESBE valve on the return, but then you take a chance of dry firing the boiler if you fire during the purge process.



ME

Paul48

Billy

No second bypass.....It ties into the boiler loop.If you're running the indirect off the boiler loop, I wouldn't worry about return temps, and if you're running it as a zone, the ESBE will protect the boiler.

Ron Jr._3

Why not use a system bypass ?

Just a simple pipe connected from the gravity zone supply ( after the circ ) to the return pipe . The pipe can be much smaller than the zone pipes and you can install a valve in there to throttle the flow . 

Paul48

Exactly

what the thermic valve would do, only it will do it all the time, under all conditions. It simply won't let return water back to the boiler, below whatever temperature you set it for.

icesailor

ODR/Boiler Protection:

All I have heard here since joining is Mod-Con Boilers and Outdoor Reset.

You won't get any ODR with a by-pass. If you have a gravity system that has been added to, and isn't balanced with the rest of the system. you get hot and cold radiators. If you have 12 radiators and ten were original, two were added, if the piping is wrong, and the new ones are added at the ends of the system, the radiators probably never get hot because the pump doesn't run long enough. If you drop the system temperature and make the pump run longer and run the water through the system as it was originally designed to do, it may then will balance out.

The valve has ODR built in. Its a thermostatic valve, As the outside temperature goes down, the valve passes more hot water into the system from the boiler. The boiler shown ran at 170. Parts of the house were unbearable and others were fridgid. On a day when it was 16 degrees out, the system was running at 122 degrees.

A boiler bypass is the same as running a three speed circulator on #1 on an oversized system. I've put in a few three way thermostatic mixers. They always took adjustment. This is set it and go. The boiler water is set with a DIP switch.

Paul48

Ice

I know you like those valves with the outdoor reset, but on a boiler with no ability to modulate, they've gotta kill the efficiency. Maybe from a comfort standpoint they are great, but wouldn't it be more efficient to just run something like a Grundfos Alpha 24/7. I have actually read some articles that say it is more efficient to do that anyway.Just tossin out ideas for discussion.

icesailor

Mixed water

The way I see it, you have a gravity system that you have no idea what the flow is or what it needs to put out heat. You have a boiler of a known quantity and a system of unknown quantity. That system was installed with a Taco 010 to the system. The 010 is the boiler pump now. The new system pump is a Wilo Star 21 set on #2 speed.

I've never seen a pumped former gravity system that was worth a crap. I've seen a few. I just helped someone out with a boiler change on an old gravity system. The smoke pipe was all rotted out from condensation.

Cost is always a consideration. If you can't use or sell a Mod/Con, you are limited to a regular boiler. The valve comes with sensors and the chip on the valve determines the system temperature.

Its simplicity in motion. Closely spaced tees are a wonderful thing. What could be more wonderful than connecting one side of a valve to the closely spaced tees and the system to the other side. And then have automatic temperature control done through the inner workings of the valve.

But whatever,

TonyS

Just put a gravity boiler

back in. A Weil Mclain EG series works well and you wont have to protect anything.

Also the system will work like it was suppose to.

icesailor

Gravity Systems:

I'm sure it works fine. Its gas. No condensation there when it starts up cold.

Do you have outdoor re-set ODR)?

Its my understanding that soon to be implemented energy codes are going to require some form of ODR.

I'll bet you a box of Dunkin Donuts that if your system has any added on radiators, they don't emit like the older ones because if the outside temperature isn't very low, or a low load on the system, the water in the system rises too high, too quickly and the radiators don't get enough flow time. With ODR, you get long run times with the circulator and it will balance out the whole system.

If you go to that building when it is 35 degrees out, and turn up the heat, and the circulator runs for some period and shuts off because it is satisfied, go around ans feel if all radiators are the same temperature and the whole radiator is warm/hot from top to bottom. If it is, then the system is working as designed. If not, it isn't working like it should. A 4-way will solve the problem and give you ODR which makes the system work better than any modern, high tech system as far as ease of comfort. I sell comfort with simplicity.

SWEI

boiler protection

Ignoring the fact that a low head mod/con with ODR is really the best conversion option here...



Check out the new Caleffi ThermoMix and ThermoBloc - see pp. 108-109 of http://www.caleffi.us/en_US/caleffi/Files/giudes/files/Caleffi_ALL-ListPrice_2012.pdf

icesailor

Mod-Cons

My comments for 4-way mixers are for those applications where Mod-Cons aren't used. There are a lot of new installs where a not so efficient boiler us used because the customer can't afford the install of a Mod-Con and all that goes with it.

As a licensed Master Plumber, I have never been a great fan of priority DHW zoning. I've  never needed it on any oil system I did that used warm start controls. It always bothered me that in the AM when trying to take a shower, the heat couldn't run while the DHW was recovering.

With a 4-Way, on a day like today where I live, it is 50 degrees outside. If I had a hot water call with priority, there would be no heat until the indirect was satisfied. With the 4-way with ODR and no priority, my system temperature might need 115 degree water, and the DHW would be running off a high limit of 170 degrees,. The amount of heating water taken off the boiler would be negligible.

scott markle_2

explanation

I'm a little confused by the photo's.



If the indirect is piped off the mixing valve ... what happens when your reset curve targets a temperature below the DHW tank setting?



I don't see much point in the P/S (closely spaced tees) and a 4-way. With an appropriate control you can use a simpler 3-way and still get the required boiler protection (with P/S) If I was going to use a 4-way I'd take advantage of the ability to have return protection and mixed flows with only one pump.

icesailor

Indirect piping:

The Indirect is piped off the high side of the boiler. The two zones/circulator were piped individually, to do their specific jobs. They still do. But I connected the supply and return of the system to the system side of the mixer. The boiler (high side) is connected to the mixer through closely spaced tees.

The boiler and indirect are controlled by the boiler controller and are always higher than the mixer. The ODR sets the lower temperature through the chip in the mixer. Even if the boiler temperature went to 180 degrees for the indirect, the sensors on the indirect and the ODR will keep the proper temperature in the system.

The boiler circulator (not the indirect circulator) and the system circulator are wired together and runb together.

I have other pictures, I just don't have them with me at the moment, 

icesailor

1 1/4" copper pipes:

Notice the 1 1/4" copper pipes. In the first picture, they go into and out of the system. In the second picture, they are tied together. Nothing was done to the 1" pipe to the indirect.

j a_2

bypass

Hello   The systems i come across are almost exclusively once converted gravity systems here in the city...I have always had good luck using a boiler bypass piped exactly like the burnham manual shows..Once you get it up to temp. you can play with the valves and watch the temp fluctuate,some call it a poor mans outdoor reset....Also  make sure you use a high flow low head pump,and consider letting the pump run at all times especially during the deep cold season...Some may agree and some may disagree But I can tell you, it works....BEST OF LUCK

j a_2

bypass

Hello   The systems i come across are almost exclusively once converted gravity systems here in the city...I have always had good luck using a boiler bypass piped exactly like the burnham manual shows..Once you get it up to temp. you can play with the valves and watch the temp fluctuate,some call it a poor mans outdoor reset....Also  make sure you use a high flow low head pump,and consider letting the pump run at all times especially during the deep cold season...Some may agree and some may disagree But I can tell you, it works....BEST OF LUCK