Where is my fuel going?

eric84

Hi Everyone - 1st time home owner/home heater here and trying to figure out where my system is going wrong.

Small 1900 sf farmhouse in Hudson Valley that we gut renovated over the summer. Blown in insulation, brand new peerless wbv-03 boiler installed with a Becket burner and a hydrostat control with outdoor reset and an indirect water heater. House has 2 zones with the original baseboards.

Problems first started when we realized the outdoor reset was not adjusting the temp properly so that it was firing at 130-140 whether 50 degrees out or 20. Plumber who installed the system finally called a tech and discovered there was "a loose connection" and supposedly fixed.

However over the last week, we were out of town and kept the house at 50 in both Zones but somehow still burned through 1/4 of our tank (250 gallon). I thought it might be heat loss but discovered that when I turn the heat off completely it will take an hour or more to lose a few degrees.

When I was home and outside temp was 30, I turned the therms up to 70, and the boiler was firing 4-5 times an hour at 135-145 temps, each cycle lasting about 4 minutes. It seemed the zones were calling for heat every 15 minutes, after slipping one degree.
Is this normal?

Only other culprit I could be thinking is the thermostats, which are non-programmable Honeywells. They call for the heat when they "anticipate" the temp is slipping off one degree from the target. That seems aggressive to me.

Is the problem the way my boiler is running or that my home isn't maintaining the target temp properly?

Fred

Most thermostats are factory (default) programed for forced air at 5 cycles per hour. Which model Thermostat do you have? Are they the round ones with the heat anticipator? If so, the anticipater probably needs to be adjusted. There are numbers on the anticipator, if you have the owner's manual, it should tell you which number to set the anticipator to for hot water heat.

billtwocase

What do you have for zones. Circs or zone valves? I would also recommend no more than a 10 degree set back for such a short period of time away. Most don't realize how long it actually takes to not only bring the room temp up the 20 degrees, but also the furniture, walls, etc

Jamie Hall

I'm not so sure that your fuel use is that far out of line... sorry about that. The place I care for -- not that far from you -- uses 9 BTU per day per degree day per square foot, and is not insulated. You might compare that with your consumption and degree days for the week you had it turned down...

njtommy

Was a heat loss done on the house?
How many btus is the boiler?

Gordy

Like @njtommy said was a heat loss done. Need that to properly size the boiler.

Sounds like boiler is over sized, and short cycling killing efficiency.

Are the baseboards original, or new to the system? If new how were they sized? If old they are probably oversized since you upgraded the envelope insulation. This is good however. Allows lower average water temps.

rick in Alaska

If I lost 62 gallons of fuel in a week, and I knew it was from my heat bill, I would move! Or at least close all the windows.
Have you considered fuel line leaks, or bad neighbors?
Rick

eric84

Thanks for the responses everyone.
My thermostat is model #: RTHL111B1001. Very Basic. Checking on the BTU shortly for my boiler but I don't believe the plumber who set my system performed a heat loss.

As I said, though we had blown in insulation put in on all our exterior walls, and did the attic floor as well. We also recently shrink wrapped all our windows.

The baseboards are half original half new

Here's a log I kept over the course of an hour to give you an idea of what's happening:


zone 1 and zone 2 thermostats set to 70:

Boiler fires 4:53pm-5:57pm (4 min)
Zone 1 calling for heat
31 degrees outside
Fires at 135-145

Boiler fires again 5:11pm-5:15pm (4 min)
Zone 1 calling for heat
31 degrees outside
Fires at 135 - 145

Boiler fires 5:36pm - 5:40pm (4 min)
Zone 1 calling for heat
30 degrees outside
Fires at 135-145

Boiler fires 5:46 - 5:50 (4 min)
Zone 2 calling for heat
30 degrees outside
fires at 135 - 145up


We are able to maintain the house at 70 when the outside temps are in the 20/30 range with the boiler firing the water from 135-145. That seem efficient, but would I be using less fuel if the boiler fired less often but at higher temps?

Does the fact that my therms are calling for heat every 15 minutes or so mean I'm losing heat too fast? Or is slipping a degree in 15 minutes normal? It seems like the cooler water temperatures the boiler is firing are able to reach the target temps but not sustain them....

Gordy

If your slipping a degree every 15 min. You did a very poor job of insulating.

How is the boiler piped? Per the I/O manual?

Gordy

How is the boiler piped?

What is protecting it from low return temps? The manual says anything below 150*. You are supplying 135-145? So your return temp is 115-125*.

Jamie Hall

I might second @Gordy 's comment on the timing -- the place I care for, with no insulation, runs on 1 cycle per hour on the thermostat. Except on very very windy days, it won't drop more than a degree in that time; usually less.

Fred

Are the thermostats on interior walls? Have you looked at how they were installed? Did the installer drill a large hole, behind them, to pull the wires through and left that hole wide open so that drafts blow up behind them? If so plug those holes with some insulation.