Oil Boiler Setup Questions

   / Oil Boiler Setup Questions #11  
Hot water heating systems are not a good DIY project unless you thoroughly understand the engineering and control nuances, much less the piping design and install. In my younger day I was a mechanical systems service technician and used to see it all. The industry has changed tremendously the last 20 years. Trying to design a system via a forum like this is iffy as we have no idea what you already have. It would be helpful if you had a friend or acquaintance in the business to assist you. The installation is not that difficult if you have good mechanical skills; it is getting to that point first.

Glycol is the way to go. Far cheaper in the long run and provides protection to the whole system in the event of a failure during freezing weather. It also acts as a lubricant for the pumps and a corrosion inhibitor. DO NOT leave the make up water source valve on unless you buy a complete automatic make up water system that maintains the mixture and alarms when there is a leak. Leaks have to be fixed quickly or your protection is compromised. By Code yhe make up water requires a Reduced Pressure Back Flow Preventor. You do not want glycol feeding back into your DWS. Most Code Enforcing Authorities require annual test and certification annually.

Remember; Boilers are one huge bomb if not maintained and serviced properly. a home boiler can destroy a whole hose and everyone in it. They are not as forgiving as an electric water heater.

I assume you are not getting a permit to do your project as they would probably require an engineered design. The average inspector is not knowledgeable on boilers except in OR State where I used to work. Therefore, they are usually not much help. Supply houses normally will not help due to liability and they sell not design and install. I had to be State licensed as a Pipefitter/Boiler Mechanic. Most Plumbers could not pass the exam so they were limited to installing hW Heaters less than 200 GL.

This is all not to scare you but to make you proceed with caution. The life you save may be your own.

   / Oil Boiler Setup Questions #12  
I understand your concerns about the 3 season room...your plans for the isolated loop should work fine. The boiler is oversized for your home (you could use one 1/3 that size) and will short cycle unless you install an outdoor reset control, which adjusts boiler water temp depending on outdoor temperatures, this will automatically take care of reducing boiler temps with seasonal and daily temperature swings. Make sure you limit the burner output to the minimum design also.
   / Oil Boiler Setup Questions #13  
The room we are isolating is really a 3 season room - the windows are very drafty, the floor is not insulated, and the pipes run underneath that room in a crawl space. Typically we close the door to that room, and it is common in the winter for the snow to stay frozen on the floor in there. We are not looking to change that with the boiler install - but we would like to use the space occasionally. I would be concerned with pipes freezing if we left the heat shut off in there for days over the coldest part of the winter. I don't think the cost is excessive to isolate - I'm looking at $90 for an extra circulator, 80 or so for a heat exchanger, and 25 for an expansion tank, plus the glycol. It seems that the cost of that would be saved in oil pretty quickly.

I had read about the boiler cycling only when called for heat - I thought from what I had read that this was primarily for DHW purposes - so that the boiler would not sit at too high of temperature over the summer, without having to touch the aquastat - but then would increase temp to keep up with heat load. I was thinking of just adjusting the aquastat depending on season - so leave the water temp low for spring/fall, and increase it some in the winter as required to meet heat demand. I was also thinking a programmable aquastat would be a neat feature - if one exists. I'm not too concerned about standby losses - I think most of that loss would be radiated to the basement, which we would like to keep semi-heated anyway. Also would be simpler to wire and control for a first cut. Would this be difficult to modify if I changed my mind later?

I understand in Europe it's popular to have a system where there is an outdoor temperature sensor and the aquastat setting is determined by the outdoor temperature.
   / Oil Boiler Setup Questions
  • Thread Starter
This web site has a wealth of info on the latest solutions for hydronic systems.

Technical Magazine | Caleffi

It is a lot better for you to read it than try to design your system via the forum.


Thanks for your input. I have been in touch with the local building inspector, and I have resources outside of this forum, if it puts your mind at ease. (I'm also a mechanical engineer - and worked in the MEP field for a short time - hated it, but that's another story). The local inspector did not want detailed documentation on the system - he wanted a price tag for the parts, so he could assign an appropriate fee. This was even true if I installed the wood boiler in parallel with the oil. In my opinion, there is significantly more safety risk with a wood boiler than oil, so I was surprised he didn't want more information on relief valves, heat dump, etc.

You say glycol is the way to go - and in the following sentences, list some of the drawbacks. It seems more hassle than what it's worth for a house that is typically inhabited with a secondary heat source. If designing a system for a house that is left alone for weeks at a time, I'd agree that glycol makes sense for the entire system, but I'm not sure the benefits outweigh the drawbacks for my application.