ast fall I purchased a ~1,900 sqft home with a Weil-Mclain WTGO-4 boiler (converted to natural gas in 2017) supplying tankless hot-water and 4 zones of heat (two hydroair and two hot water baseboard zones). We occupied the house maybe 10-12 days out of the month, yet our gas bills were:

• Oct: Avg Temp: 46 - $103
• Nov: Avg Temp: 32 - $230
• Dec: Avg Temp: 36 - $211

I know that oil-to-gas converts aren't that efficient, however, I think these bills are still a bit high for a furnished but barely occupied house. The house isn't the tightest construction but it by far isn't the worst. While home, the stats are set to 66-68F during day, 60F at night. While away, the stats are set to 52F. ALSO; these bills are in line with what the previous seller had, and they occupied the house even less than us.

Here is a list of some things I think are the culprits, but I am unsure how realistic these ideas are or how to prioritize fixing them. Can the experienced/pros give me some feedback/recommendations/warnings (if I am doing something stupid)?

1. Running the boiler too hot. Yes, keeping the boiler at 205 (previous owner's settings) gives me toastier hydroair, but I found 180F, even when we hit single digits Fahrenheit outside, still had capacity to heat the house.
2. Using a warm start boiler; I reduced the Low on my aquastat from 160 to 140F (this supplies our DHW). Maybe one day it will be worth converting to a cold start (no clue if this boiler can handle it) but I am not sure if those gas savings offset the potential increase in maintenance costs and the costs of indirect HW install. Either way, I think zones call for heat enough during the winter that the boiler will probably stay pretty warm.
3. Improperly wired relays. Since I have been away from the house, I have been thinking about how the relays are wired up. Zone 1 circ goes off of the aquastats control and I think all other zones may be unnecessarily activating the zone 1 circ. upon calls for heat (but calling for burns through the aquastats TT terminals). Circulating hot water to a hydroair zone that isnt calling for heat has to be pretty wasteful. I am installing a new multizone relay this weekend.
4. Drafty Room: previous owner put on an extension that is unbelievable drafty. I know it is insulated (maybe underinsulated?) but I have no idea what they did. I wish I realized this before redoing the entire room. On cold nights, I can see this zone calls for heat once every hour or so at ~55 degrees stat setting. It is a 300 sqft room on slab that has hydroair for heat. Sealing up this room should be a priority, I know.
5. This last theory is new. I was reviewing the Carlin Burner manual while preparing for my rewiring this weekend and saw the instructions called for two fresh air vents to outside in the boiler room; one 12 inches from the ground and the other 12 inches from the ceiling (when vented outside). Right now, there is only one vent in the room, which is a small 12x5x10 ft utility closet on ground level that is only accessible from the outside. Could this lead to poor burns? I had the gas company out back in November and they were useless. They said my CO levels are perfect, so I am most likely burning okay. The gas conversion is under 2 years old right now, but maybe this boiler is due for a tune-up burn analysis.

Original thread..... weil-mclain-boiler-updating-original-relays

 

This should be part of your other thread as now the same questions are going to be asked again.... especially about wiring. You're asking about boiler efficiency and talking about a drafty room. Sealing up, insulating and eliminating drafts is your first step to increasing efficiency. You have not told us where you live either.

Let's keep the wiring and controls in the other thread and we'll see how this goes.

 

There is no single culprit. Residential heating systems are like any budget. Many factors add to it. Reduce heat loss and and find more cost effective ways to do things. Old oilers can be made more efficient by reducing nozzle size, adding electric stack vent and OCR.

A good starting point is $156 out-door-reset/ aquastat. OCR's automatically vary water temp bases on outside temp. Have separate settings for water max high and low temp, delta-T.

ODR is no brainer, saves 5% to 20% on fuel costs. Quick, easy DIY install. Fast annual pay pack is endless, year after year!

Read the manuals.....Install Sheets and Install Instructions:
https://www.supplyhouse.com/Tekmar-2...iler-4150000-p

 

Located on shoreline CT. Sorry about that.

Thanks for the feedback. As suggested by PJ, I will leave wiring discussion to my other thread. Just as a note, that thread is about me updating my relays, with the goal to clean the mess up and allow easy hook up of an ODR in the near future.

I do have a couple of questions, probably dumb, so please forgive me. Is OCR a typo or is it something different than ODR? I definitely plan on installing the Tekmar you linked to or the Taco PC700 (although Ive read that it is essentially a more expensive Tekmar with less features?).

Also, can you provide more information about an electric vent stack? I am not familiar with that.

 

Hi pb,
I'm not an hvac pro but come from the home efficiency side. Reducing heat loss is a win from all sides and should be done before any new system is installed.

One bit of advice I like to emphasize is to get your improvements lined up so you don't make one impossible while doing another. Some improvements can make others easier or harder.

Smile winter is on the downhill side.

Bud

 

Thanks for the feedback.

I just got my bill in for Jan 11 - February 11:
-Average temp: 31F - > $237

We were at the house for 3 days during that period and when we weren't there, all stats were set to 55F.

Its probably impossible to say without knowing a lot more details about the house but is there a ballpark amount of time the structure should hold temp if its decently insulated/sealed-up?

Regarding the four zones in my house: hydroair zone 1 covers the upstairs and then also has a vent in each room of the original structure downstairs. In the original structure downstairs, the zone 1 hydroair gets help from two original baseboard zones. I have an Ecobee on hydroair zone 1 and I see that it isn't running that often. I replaced the mercury stats on the baseboard zones with digital stats and have watched them when home; they seem to get the zone to temperature and hold it well. I also have three extra sensors hooked to this Ecobee that confirm the upstairs and original structure downstairs maintain target temp, and at the least, the upstairs hydroair isn't running that often to maintain it. I think there is a good balance of the 1 hydroair zone and two baseboard zones maintaining temperature in the original structure of the house.

Now the extension zone downstairs. This room is the bane of my existence. When we bought the house back in October, I converted it from a home office to a family room. During the conversion, I went into the ceiling and walls a bit and can confirm, they have fiberglass insulation and vapor barrier, although I didn't note the R rating. I have attached a quick schematic of the room.

Couple of things to note about the room. The three feed vents are on the ceiling, the one large return vent is on the upper portion of the wall. The room is on a slab. Has 3 windows and a sliding door, all new construction and efficient. Quick inspections I did of the room I didn't notice any drafts in the structure. Only thing I could think is its coming in through the vents, although nothing that obvious cause I have felt around them when the unit is off. The blower for this zone is in the unconditioned but insulated utility closet. As much as I can tell, the unit is fully insulated. The three ceiling vents do blow air when engaged, but it does take 5+ minutes to get hot air from them. So of course, room temp drops by 3 degrees before and heat comes in.

I am also including the Ecobee stat data for this room. Dont mind the missing data in the plots, of course ecobee has been having server issues throughout January......

Is this room cold because the blower is in an unconditioned space? At least the return vent stack is insulated, so I am guessing the feed are as well. Maybe there is a gap in the feed vents and a pressure differential is drawing in cold air? I really have no idea but I am getting sick of paying more to heat a cold, unoccupied house than people who live in pay. This is only complicated by the fact that I can't pay someone to come and inspect and I hardly have time to inspect myself.

 

pbct2019: OCR was a typo mistake, should have been ODR

Taco PC700 is rebranded Tekmar 256. The only difference is packaging. Tekmar 256 can be easily wired into any system.

Most ODR installations use 2 wires for 24 VAC and 2 wires from ODR relay to start burner. Usually systems have 24 VAC that can be used.

The PC700 4 wire connector plugs into Taco SR 504 controls. That may be inconvenient location to view and change ODR settings. My 256 is eye level on side of boiler. Pushing "Item" button steps display through Out Door Temp, ORC target temp and Actual Measured Boiler temp.

Regarding your zone valves, most have switches that close when valve opens to activate circulator. In multi zone systems with one circulator, valve switch leads are wired in parallel. One group goes to 24 vac and the other to circulator relay. Second side of relay goes to other 24 vac transformer terminal.

Below is link to 4" gas burner stack damper. They come in different sizes. Oil burners use different models. I found 18" long vent pipe from boiler to auto vent was heat loss and wrapped in fiber glass insulation.

https://www.supplyhouse.com/Field-Co...per-11701000-p

 

I am guessing the chimney damper purpose is it reduce heat loss up the chimney? I do have a barometric damper on the chimney that is wired to the burner; my understanding is this is more for improving drafting to improve CO/exhaust flow up and out.

How is the safety of the chimney damper? Seems pretty bad if that motor fails to upon when burner fires?

 

You have a draft regulator on your boiler because it was originally oil fired. If it was a packaged gas boiler you would have had a vent damper on there. They are to help with the heat loss after the burner shuts down. There is a story behind why they come with a gas boilers but they are more trouble than they are worth and we'll both be in the ground before you get any payback.

You are right, if the crap out and they often do your boiler will not run.

Just my opinion.

 

pbct2019: How is the safety of the chimney damper? Seems pretty bad if that motor fails to upon when burner fires?

Electric vent dampers have switch contacts wired to prevent burner from starting until vent is open.

Electric vents also have manual switch to keep vent open at all times allowing burner operation.

Worst case, motor activator module can be removed ( 2 screws) and vent shaft clamped in open position. The "vent open switch" leads wired together enabling burner operation.

 

So I finished installing a Taco SR504 relay this weekend to replace the old Honeywell relays that were in place (that thread is linked in my first post above). During that switch over, I discovered that Zones 2, 3a and 3b WERE NOT wired to the aquastat at all. Zone 1 was wired directly to and controlled by the Aquastat.

Since I have tankless DHW, I have a triple Aquastat. My understanding is a call from heat from any zone should initiate the boiler heating up to the Aquastat's HIGH setting (180F), which is maintained until heat call is satisfied. If there are no calls for heat, the Aquastat's LO (140F) setting is in control. Meaning, the boiler will maintain this LO temparture to (1) avoid condensation and (2) maintain temp to supply DHW.

It turns since zones 2, 3a, and 3b were not wired to the aquastat, so all they would do is circulate water to their zones upon call for heat. This would eventually drop the boiler to the LO temp, which then the boiler would maintain. Thus these three zones were only getting 140F for heat, which was really insufficient.

This problem is further compounded by the fact Zone 3B is leaky and calls for heating every 1-2 hours, which mean it had the boiler constantly firing to maintain 140F while it struggled to heat its zone with lukewarm to cool air.

Hopefully shoring up the leaks and resolving the wiring will help! Still welcoming anymore tips or advice

 

Now you understand why that ZC/ZR is important when wiring up added zones to a boiler with a tankless. Unfortunately there are techs that don't even know what they are for. It is one thing to try to explain it but as you physically did it now you see the results. I think you'll see your heat will be better at the higher temp instead of your low limit.

Good job, thanks for the update.