Indirect tank off oil boiler vs. standalone tank


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Old 05-21-18, 08:22 AM
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Indirect tank off oil boiler vs. standalone tank

Existing setup is an old oil steam boiler with tankless coil for hot water. Upon replacing, we are torn between getting a stainless indirect tank or a standalone tank with its own oil burner.

It seems like in the summer, the boiler will have to heat up from cold to keep the tank satisfied (which seems like a big fuel cost for a 25 y/o boiler), but with the standalone, it's another oil part to service, and much more heat loss up the flue.

Not sure if gas is available yet. If so, we'll be going with a mod/con unit and either on-demand unit or indirect tank.
 
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Old 05-21-18, 03:09 PM
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If gas is or becomes available, I would go with a stand-alone gas water heater. But with oil, I'm not so sure. And, of course, if natural gas is available, then I expect that you will promptly replace your existing oil-fired boiler - just for convenience as well as for fuel cost savings.
 
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Old 05-21-18, 04:38 PM
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Just found out gas is there, so this will be an easy decision.

Tx.
 
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Old 05-22-18, 07:24 AM
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Most economical set up is with separate fired water heater. Direct fire it in summer and use tankless coil with circulaltor to heat water in winter. At season change just flip switch.

Common round water heaters are very inefficient compared to boilers. This way get best of both.

Tankless coil hot water source to storage tank set up increases capacity of system.

Have used this system for years. Only maintenance was rust particles in city water wasted away Taco 007 plastic impeller. Recommend using $39 "whole house water filter" in line to hot water tank.

https://www.supplyhouse.com/American...-Relief-Button
 
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Old 05-22-18, 03:08 PM
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What do you mean when you say "tankless coil with circulator"?
 
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Old 05-22-18, 06:00 PM
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Pipe tankless coil out to tank inlet and tank outlet to tankless coil inlet.

Install small circulator and check valve to circulate hot water from coil to heat tank water.

Use tank aqusatat with 5 deg F delta to activate circulator.

$15 PID controllers are great aquastats for this:
https://www.ebay.com/itm/Dual-Digita...kAAOSwjL5ZFE0N

In summer flip switch and aquastat starts tank heater.
 
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Old 05-23-18, 03:37 PM
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S,
I feel I must contribute a little something to this post that doughess has neglected to mention.

First, this is done in some situations by qualified people. You can use a separate hot water heater or something they call an aquabooster which is simply a storage tank without a burner for extra hot water storage of tankless hot water.

It isn't quite as simple as doug makes it out to be if done correctly.

The main thing and most important is the pump used to circulate the water from the coil to the tank and back to get reheated.

Any pump being used for domestic water, either hot or cold must be a bronze pump.You NEVER use a cast iron pump, which Doug is most likely using, since he mentioned a plastic impeller, which is wrong.

After all, you would never drink water from a cast iron pipe or cook in preheated water drawn from a faucet to cook with as some people do.

The pump must be Bronze and there are valves that must be properly placed in order for this system to work properly.

I do agree with him that a boiler is much more efficient than a hot water tank and the tank basically has a 6 year warranty which should tell you something.

At the end of the day all this becomes moot because at least in my area you cannot get a gas boiler with a coil. They discontinued making them because of the poor recovery rate with gas.

This set up would be for oil only because they're the only boilers that come with a coil. Gas would be 2 separate units unless you install an indirect water heater instead of the stand alone tank. The indirect acts as a separate zone off the boiler and is the most efficient way of making hot water today.

Just my thoughts, hope this helps a little.
 
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Old 05-23-18, 06:07 PM
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Qualified is a meaningless phrase in the USA today. Spott may think there is such but the incompetance that I find in “professionals” is real.

This system is Not a aquabooster. It uses water heaters. Not just a storage tank. The whole idea is to use more efficient boiler for heat in winter and less efficient water heater in summer for heat.

As for Spott lecture on bronze for water pipes, our city water system with miles of cast iron pipe and steel storage tanks does not follow it.

Water heater has no coil. This system works with oil, gas or electric water heaters. Tank has ordinary inlet and outlet. Water from tankless coil just circulates until tank aquastat reaches setting.

Replaced Taco 007 cast iron pump with plastic impeller once in 20 years. The $39 whole house water filter has a clear plastic body. It is turd brown with all the rust particles that has not impacted flow.

My tank was new in 2002 with 6 year warrenty. Replaced $25 anode a couple of years ago. Whole house filter keep sludge out of tank proloning life.
 

Last edited by doughess; 05-23-18 at 07:03 PM.
  #9  
Old 05-24-18, 01:36 PM
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Doug,
First off this is a DIY sight and people seeking answers basically do not have your knowledge and I notice in some of your responses you only give an outline of solutions you recommend and my responses are geared to you giving the whole story.

For instance your response to my 6 year warranty comment. You mention your tank is 16 years old but you never mention in your o post about changing the anode rode.

You and I and most people in the trade know what that is but a DIYer wouldn't know an anode rode from a fishing rod. If you didn't do regular maintenance on the tank it would have been history a long time ago. This a fact that people should know before diving headlong into project.

Your response to my Bronze pump is a comment about the pipes in the street used to deliver water. You have the foresight to use a whole house filter and seeing what is being caught before it gets into your house water system is evident about the pipes being used. Those pipes are hundreds of years old and that is what was available back then but a DIYer probably wouldn't think of installing a filter.

You have a filter for the incoming water but why would you use a cast pump inside where there is no filter. You don't use cast iron pipe to go to your faucets, why would you want water running through a cast iron pump.

I don't know the codes in NY but in MA where Slade happens to reside Bronze must be used on all potable water if you're pulling a permit.

If you were to read my post fully I understand a water tank has no coil. I only wanted to mention the different options that were available and if going with gas a boiler with a tankless coil is no longer available so if going with a gas boiler your choices are more limited to a stand alone or indirect tank.

Qualified is a meaningless phrase in the USA today. I would love to disagree with you but you are exactly right. I should have said so called qualified or licensed person.

Unfortunately in our trade quality is a fading term as is pride. I know people outside the trade like DIYers that do better work than so called pros because they care more about what they're doing.

As I said, those were just my thoughts and you have more than a basic knowledge of things but in my opinion some of your responses are over simplified of what the people are in for because you are doing constant maintenance to your equipment to keep things running as well and as long as they are but you neglect to mention that in your posts and I think DIYers with less knowledge taking your advise aren't being fully informed and may be in for some surprises but again those are just my thoughts.

Galvanised steel or iron pipes
Galvanised steel or iron is the traditional piping material in the plumbing industry for the conveyance of water and wastewater. Although still used throughout the world, its popularity is declining. The use of galvanised steel or iron as a conveyer for drinking water is problematic where water flow is slow or static for periods of time because it causes rust from internal corrosion. Galvanised steel or iron piping may also give an unpalatable taste and smell to the water conveyed under corrosive conditions (WHO 2006).

Have a good Memorial Day.
 

Last edited by spott; 05-24-18 at 01:58 PM.
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Old 05-27-18, 06:58 PM
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Fifty years ago when my home was bought I had never worked with oil burners. After professional service guys messed up repeatedly became a DIYer.

Slade8200 thread is about classic problem on residential boilers with tankless coil ... the best way to get DHW in summer?

I posted a solution that is practical and economical which has worked well for years.

My one problem in 20 years was a $90 Taco 007 pump. Spott goes off on a tangent about bronze pumps. The thread is about DHW in summer, not pumps or pro's and con's of pipe materials..

After (not before) removing and seeing the impact of rust particles on the 007 to prevent reoccurrence installed $39 whole house filter. https://www.supplyhouse.com/American...-Relief-Button

With 12 plus years on a 6 year warranty water heater I put in new anode. That is not "regular" maintenance.

Spott: "you are doing constant maintenance" Doughess comment: This week I turned the boiler off for the summer after 719 hour season run time. Season maintenance time zero. Vacuum gauge on oil filters reads 3 "hg so they do not have to be changed! In prior year only maintenance was replacing nozzle.

My system is designed for reliable operation, easy diagnoses of problems and quick repair.

I post on DIY.com to help readers with straight info. Have never worked in HVAC but In an earlier career designed systems with industrial heat exchangers. Boilers are heat exchangers, no magic to them. Keep them clean and remember what goes up the chimney is wasted.
 
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Old 05-27-18, 08:20 PM
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I see things are getting a little heated in here.

Doug.... Although your setup is very high efficiency it is not for most people. I consider it a more costly install and would require more knowledge then most installers have. I also feel that since it's slightly more complicated the repair and maintenance could become an issue.

At this point that we should wait to see if the OP has any further questions and address them directly.
 
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Old 05-28-18, 03:28 PM
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No problem here Pete. As I said, those were only my thoughts but apparently Doug got up on the wrong side of the slab.

As I said before we all work differently and whatever works best is for you is the way to go.

Congrats Doug on your fine season.
 
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Old 05-28-18, 05:24 PM
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If I read Doughess' idea correctly, when the boiler has a domestic hot water coil then you can take water from a stand alone water heater and route it through the boiler and send it back using a circulator. In winter you can turn off the water heater heat and the tank will work like an indirect storage tank. (In summer you need to shut off the boiler loop with a valve so domestic water does not drift into the shut down boiler loop and come back cold ). In essence the stand alone water heater burner and the boiler operate as heat sources in parallel.

All this does not work with a boiler that does not have a domestic HW coil since boiler water and domestic water may not be commingled.

More intuitive solutions have the heat sources in series for example incoming (cold) domestic water goes through the boiler coil first and then into a stand alone water heater (tank or tankless). With a series system the "last" unit has to be able to deliver the domestic water at the desired (hot) temperature 24/7/365 which can lead to heating inefficiencies.
 

Last edited by AllanJ; 05-28-18 at 05:48 PM.
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Old 05-29-18, 01:12 PM
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Allanj is wrong with:
water heater burner and the boiler operate as heat sources in parallel
The 5-22-18 Post #4 explains this system:
Most economical set up is with separate fired water heater. Direct fire it in summer and use tankless coil with circulator to heat water in winter. At season change just flip switch.
The most economical heat source is used in a season, never both simulaneously.

A check valve in circulator loop prevents vents back flow.
 

Last edited by doughess; 05-29-18 at 02:12 PM.
 

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