Adding LWCO to old HW Boiler

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  #1  
Old 11-12-20, 03:42 PM
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Adding LWCO to old HW Boiler

I've been doing a little reading on the function of an LWCO and it certainly seems like a worthwhile safety device that my 45 year old boiler system does not have. It sounds like ideally you want it to be in the boiler or failing that, as close as possible to where the hot water supply side exits the boiler and to be a manual reset. In my case, I think that would mean installing a T in the black pipe line, which would require removing the pipe from the boiler. I'm concerned that disturbing something connected for this long would be asking for trouble. Is there anything available that allows you to drill a hole in the pipe and install a fitting (tapping the hole, etc.). Are there any alternatives to mounting it here? Would it prone to false calls if mounted up near the inlet to expansion tank?

One more question, the system is run by a Honeywell R8182D triple aquastat which was replaced back in 2011. It works fine but I know these old relay boxes don't last forever. I also run an indirect tank off of the DHW coil if that matters. If you were going to replace this with a modern, solid state control, what would you recommend? Do the new controls have the smarts built in so an external LWCO isn't needed?





 

Last edited by PJmax; 11-12-20 at 05:38 PM. Reason: reoriented/resized pics
  #2  
Old 11-12-20, 04:38 PM
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Not quite. The LWCO needs to be installed in piping directly connected to the boiler, but above the elevation of the normal high level of the water.
 
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Old 11-12-20, 05:02 PM
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How about just before the pressure relief valve?
 
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Old 11-12-20, 05:57 PM
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LWCO's are used on steam boiler where proper water level is important.

Hydronic system cold water feed valve is left open so system stays full, and water level is not an issue.

Rather than replacing old technology, immersion bulb aquastat, up grade and save up to 20 % on fuel costs with out-door-rest/aqustat. ODR's provide both hi and low level control to 1 degree F with adjustible Delta-T.

Tekmar 256 ODR has full features, lowest price and best buy. Read Submital Sheet and Instructions on link:

https://www.supplyhouse.com/Tekmar-2...iler-4150000-p

Taco PC 700 ODR is rebranded 256 for $80 more:
https://www.supplyhouse.com/Taco-PC7...-Reset-Control
 

Last edited by doughess; 11-12-20 at 08:48 PM.
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Old 11-12-20, 06:38 PM
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Thanks Doug. It may be a dumb question but does the outdoor reset replace the old aquastat? My impression from reading the submittal is that it works with the existing control.
As for the LWCO, after reading this and noting that at least some fill valve manufacturers warn not to leave it open, it made me wonder. https://heatinghelp.com/systems-help...pen-or-closed/
 
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Old 11-12-20, 08:36 PM
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An outdoor reset works with an aquastat that can use that signal.... wouldn't be your old one.
As the outdoor temperature changes.... the reset changes the boiler temperature.
As it gets colder....the boiler temp goes up and warmer it goes down.

As to that article..... there are arguments for and against it. I normally leave the fill valve active unless it's over pressurizing the system.

 
  #7  
Old 11-12-20, 08:57 PM
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Out door reset is aquastat with temperature adjusted according to second sensor on north outdoor wall.

ODR changes boiler water temperature to level needed for home heat load based on that.

Typically system is designed for 180F water on 0 F design temp days. When outside is 50 F, 140 F boiler water is adequate for heat load. See chart in installation data.

Home is a actually more comfortable because gradual temperature change is unnoticed.
 

Last edited by doughess; 11-12-20 at 09:24 PM.
  #8  
Old 11-13-20, 04:18 PM
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M,
The sight below is the part you are looking for. Hydrolevel-3250P will replace your old style aquastat with an update that includes your LWCO. Steam boilers are not the only boilers that use LWCO's, in fact some areas actually reqiure them on hot water boilers. As I have heard on here many times by the same poster that is old time thinking.

It is an age old debate whether to leave your feed valve on or off. More people are putting heat in the basement where the baseboard is below the boiler so if a pipe lets go the LWCO will help save the boiler and that is just one reason.

As far as the ODR goes you still need an aquastat to control the boiler. As Pete mentioned it only adjusts the water temp to compenstate for the changes in the outdoor temp. I have tried in every way I know to explain this to one of our posters including giving the ph. number to the maqnufacturer so they can explain it but it has fallen on deaf ears but Pete is correct so don't get rid of your aquastat and expect to replace it with just the ODR.

Anyway, I believe this is what you are looking for and would require no change in piping. By the way that tank you have for your domestic water is called an aquabooster and not an Indirect if you are looking to replace or change. There is a difference. Your tank is connected to your coil for extra capacity, most times because your coil cannot keep up with demand for various reasons.

An Indirect is a seperate tank also but runs as a seperate zone off your boiler and is very efficient and does not need the boiler to maintain year round temps.

You can read the info below on these items.

https://www.supplyhouse.com/Hydrolevel-48-3250-Model-3250-Plus-Fuel-Smart-Hydrostat-for-Oil-Boilers-Temperature-Limit-LWCO-Boiler-Reset-Control

https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=hydrolevel%20LWCO?searchText=hydrolevel+LWCO


https://www.supplyhouse.com/Hydrolevel-EW-202-Hydrolevel-Electro-Well-Extended-3-4-NPT

Hope this helps a little.
 

Last edited by spott; 11-13-20 at 04:43 PM.
  #9  
Old 11-13-20, 11:03 PM
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The modern way to set up hydronic boiler is different than how old timers did it.

Tekmar 256 aquastat with outdoor reset costs $158 and saves up to 25% on fuel cost providing with many other benefits and features.

Honeywell 3250P costs $156. For out door resent pay $158 more for Out door sensor add on kit totaling $314. https://www.supplyhouse.com/Hydrolev...-and-3250-PLUS

My 60 year old boiler Honeywell aquastat was removed when Tekmar 256 ODR was installed. Has run well for years with 1 degree F water temperature control without "need" for a separate aquastat.

And, with water feed left on has never run low on water, so never wasted time and money on LWCO.
 

Last edited by doughess; 11-13-20 at 11:22 PM.
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Old 11-14-20, 08:19 PM
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Thanks very much for the info guys. I read up on both, the Tekmar 256 and the Honeywell 3250P. It would be nice to upgrade the whole enchilada (including ODR) for only $156 but I get the impression that the Tekmar 256 is an ODR only and I would still need an aquastat. I think Doug meant to use it with my old aquastat. It is clear that the 3250P is an aquastat and you must buy the add-on ODR for that capability.

SInce I do have a zone in the basement, I would like the piece of mind an LWCO would add and I'm hesitant to leave the water feed open. Even with the 3250P full set up, I think I would still need to break into the plumbing to install the 'electro well' for the LWCO, wouldn't I?

As for the aquabooster, you were 100% on that (coil cannot keep up with demand). When I finally have to replace this boiler, I'll go with an indirect.
 
  #11  
Old 11-15-20, 09:12 AM
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M,
There is no need to alter your plumbing with the 3250. The new well you would need in order to activate the LWCO feature will go where the old well is now for your current aquastat. Remove existing well and install new one in boiler in same location.
 
  #12  
Old 11-15-20, 03:31 PM
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Let's make this simple. I pulled old Honeywell aquastat bulb out of well on boiler tankless coil header.

Whatever Honeywell aquastat wires went to now go to Tekmar contacts

Put Tekmar ODR sensor in boiler aquastat well.

Put outside sensor on north wall and connect 2 wires from it to Tekmar display control box.

Tekmar also need 24 VAC from someplace.

A more accurate name for ODR is Out-Door-Reset-Aquastat. They are aquastats that change boiler water temperature to match varying loads due to changes in outside temperature.

I also have a basement heating zone element that is lowest point in 8 zone system. LWCO is titts on a bull. Cannot envision a situation where it would do anything. For steam boiler LWCO is very usefull. On hydonic systems total waste.

Final point, before turning off boiler for season shut off boiler feed valve. When boiler cools pressure drops for summer.

In fall turn on boiler. As water temperature rises so does pressure. When burner shuts off, open water feed valve. B&G pressure regulator and Watts auto vents on elements take care of any pressure issues.

Set up things to make old age ife easier,
 

Last edited by doughess; 11-15-20 at 03:53 PM.
  #13  
Old 11-16-20, 03:47 PM
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Thanks for clarifying things guys. Since I use the boiler to heat the DHW tankless coil, I never shut off the boiler. I've also read that when running an old boiler, it's a good idea to minimize extreme thermal cycling or leaks can develop at the sections. Old wive's tale? Electricity is pretty expensive here in the north-east too, so I wasn't thinking of switching to electric DHW (and we don't have piped in natural gas).
 
  #14  
Old 11-16-20, 08:01 PM
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All boilers thermo cycle. Don't worry about it. Mine has been doing it for 60 years. Counter now on burner reads 49,943 cycles after couple of years.

Rather than running boiler all summer Mike C5 might consider a hybrid DHW system.

In winter heating season, use tankless water circulated with small Taco 007 pump activated by aquastat on direct fired water heater tank aquastat to heat water. This also expands DHW capacity, at lower cost than direct fired.

In summer, with boiler off, direct fire water heater. With high electric heater costs, savings in would significant since only powered in summer.
 
 

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