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Hot water system costly and cold

Hello all,

I am in a bit of a pickle and I'm thinking its partially my own fault.
I have a house thats heated by a Utica Boilers hot water system (MGB 200HD) and was formerly controlled with a honeywell T87F. It was using what seemed like a lot of natural gas...to put it plainly, the bill was considerably higher than the 50 year old gas fired hot air system in my parents house, while the heat was only set at ~55ish degrees (I am not living there currently).

I replaced the old honeywell with a new one (RTH 2300B) and now the heat just won't come up. I can raise the heat to 70 or above on the thermostat, and the furnace comes on like it should but the temperature won't get anywhere close...63 seems to be the limit. When I took off the old thermostat I didn't pay attention to the wiring (stupid me) thinking it would be more straight forward in a home built in 1950 than my parents house which is twice as old. When I look at the old thermostat, I am only really seeing metallic connections for two wires, I presume the red and white. The third wire (green) *Might* have not been connected to anything, yet I have all 3 hooked up on the new thermostat. Any danger in trying just the two (red and white)? At the emergency shut off switch on the boiler I am only seeing two wires connected, a red and white with a third bare wire wrapped around the bundle. The boiler, btw, was installed by a professional several years ago. I am currently considering this a thermostat problem because the old one would raise the heat...it just cost a small fortune. I do still have the old one, but not remembering how it was connected...well, you get the idea.

Also, the 2nd floor is and was considerably colder than the 1st. The boiler is in the basement. I suspect I need to bleed the radiators: I did it once already and it made little difference, but at the same time the radiators already weren't getting much warmer. Never having had a hot water system before, do you usually need to bleed the radiators several times to get all the air out?

As you can see, I am new to all this, so please bear with my ignorance. Very much hoping you all can help me out or at least point me in the right direction. A professional is not in the cards at this moment.
Thanks for your time.

Re: Hot water system costly and cold


You might want to try connecting the T87F to the red & white wires & make sure you mount it level on the wall (using a spirit level if you have one).

Try to remember that the t-stat is simply an on-off switch & the T87F is a very simple unit that has a drop of liquid mercury inside that shorts the two wires together temporarily when the room calls for heat.

You also want to bleed one or two rads on the top floor (all of them on the top floor, if you get the chance)---TO MAKE SURE YOU GET SOME WATER OUT OF THEM when you open the bleed valve.

If you don't get any water out of the top floor rads when you open the bleed valve, make sure the water supply line to the boiler (right near the boiler) is open and the altitude gauge needle on the boiler reads at least 12 psi (there are usually two needles inside the same gauge--one indicates the water temp, the other the water altitude or pressure).

If you still don't get any water out when you bleed the upper rads, post back; we will have to make a minor adjustment on one of the boiler valves to make sure water is getting to the top floor & there's no air in the piping.

The Utica MGB 200HD is rated at 160 thousand BTU/hour heat output & should be large enough to heat all but the largest of houses---what is the total sq. footage of the building????? Does it have insulation in the exterior walls & the attic????? What is your general location????? Do you have double pane or storms on all the windows of the house?????

Any, or several of the above questions may be the cause of your burning an excessive amount of fuel.

Please post back after you've done the two tasks listed to report your results.

Re: Hot water system costly and cold

Ok, I'd be happy to oblige but I have a few questions.
For starters, the backing of the t87f has no indications of which wire connects to which screw. I can remember how it sits in relation to the wall, and there is a mark to indicate the top of the backing plate, but nothing differentiating the posts.

So, if I connect the red and white wire in reverse order, will I do any damage to the boiler? I suspect looking at this
That I will just be connecting the red wire to the screw on the left and the white to the screw on the bottom, but I am not sure if there are any differences through the years of its production? This thermostat could theoretically be as old as the house (1950).

Not at the house now, will test ASAP...any thought on me disconnecting the green wire from the current thermostat? Again, my main concern is for the boiler (obviously)...

For your other questions, I am in CT, its quite cold right now, old windows, about half have storms, walls are insulated, attic is not I would guess house is approximately 2500 sq ft with the attic being the only unheated space..basement has electric heat.

Re: Hot water system costly and cold

No need to worry the boiler won't be damaged by connecting the T87F---just connect the red & white wires any which way---the green can be left unconnected.

If the house is indeed approx. 2500 sq.ft., the size of the boiler you have now is about twice what you need for that building; the lack of attic insulation and the condition of some of the windows is also letting out a lot of heat, so future projects on your part should include attic insulation & rehab of the faulty windows---most of this can be done as a diy project if you are strapped for $$$.

Use caulking compound with a gun applicator and plastic sheeting to fix any drafty windows that are letting in any cold air.

Once you get a tight house the gas bills will go way down & the building will be much easier to heat with less gas used; the boiler might be able to be downrated (downsized) by approx. 20% by installing smaller orifice gas burners.

Re: Hot water system costly and cold

Thank you sir (or ma'am), I do appreciate the help. I'll be trying out the old thermostat tomorrow and reporting back.

My thought process on the heating bill was basically this...parents house is a circa 1900 colonial...no insulation except the attic, 2.5 stories, mostly original windows and a forced hot air system that is approximately 50 years old. The last heating bill there, at the same rate for natural gas, was almost half of the house with the boiler. So something is amiss.

I will say this though, the whole reason I was replacing the old T87F is because I thought it wasn't working properly...set to 55degrees the house would linger around 60/62F, set it up to 65 and it would be more like 70. But, in hindsight, at least it got warm LOL. I figured it to be the cause of the higher heating bills, with my thought process being something newer would be more accurate and thus more efficient.

Thanks again.

Re: Hot water system costly and cold

I have never seen a thermostat that didn't have letters and numbers identifing the terminals. It would be impossible to hook them up properly. They are usually on the subbase next to each terminal. All Honeywell stats have them. On some stats (not the T87) that don't use a sub base, the terminals and identifiers are on the stat itself. These letters and numbers have been standardized for probably over 50 years, so they are usually the same for different models and brands. Here is a list:
contacts on other systems
Old Label_________New Label__Description
R,RH,RC_____________R_____ 24 VAC Transformer hot side
Y,Y1 or M____________Y_____ Stage 1 Cooling/Heating Circuit
F or G________________G_____ Fan control relay
W,H,or W1______________W______Heat first stage
C,X or B_______________C_____ 24 VAC, Transformer Common Side
Although the terminals are color coded to match the wire colors, many installers don't have the proper wire for the system and will substitute one with different colors. R=RED,Y=YELLOW, G=GREEN,W-WHITE, etc.
As Nashua said, the red connected to the white is typical for bringing on the heat. You do not even need a stat just wire nut the two together and the boiler should run continuously until the water teperature thermostat on the boiler shuts off the flame. It is very possible the third (green) wire is not used. Find the wire where it enters the boiler and see if the green is hooked up to anything. Many of these old systems only had two wires.
You did not mention what your hot water supply temperature is. This is critical to the system having the ability to properly heat the house.

Re: Hot water system costly and cold

No updates just yet, I ended up having to go into work unexpectedly, so hopefully tomorrow.
Thanks again for the help.

And I assure you, as I look at this old t87f there is no indicators on either connection on the wallplate for which wire goes where, nor is there (that I can see) on the unit itself.
On the back of the thermostat there is a series of numbers, going from top to bottom but they do not align to either connection screw, or anything else for that matter. They are 8, 4, 2, 1 on the left and the letters I and P on the right. I'll dig up my camera and post pics tomorrow.

Re: Hot water system costly and cold

Please click on the thumbnail to enlarge it.

This is a simple non-switching sub base for a T87F stat. It has three screws to connect your wires to. The three threaded holes are where the stat screws connect.
The three screws are labeled: Y yellow for cool, W white for heat, and R for red 24 vac. The W is in the shadow. It also has a 4,5, and 6 for the really old system of numbering. Most stats have a subbase, and they cannot be used without them. Some stats have the terminals on the stat and no subbase. Either way, they must be marked with a letter or number or no one would know how to connect them.

There are other subbases with more terminals and some have switches on them to select different modes of operation.

Re: Hot water system costly and cold

You can download the manual for the stat.

Technically on a 2 wire setup -- it doesn't matter if the wires for R&W are reversed on the thermostat it'll work fine.

Just a thought --- has the anticipator been correctly set?

Re: Hot water system costly and cold

OK, sorry for the delay, weather / work is to blame.
I went over to the house today, and of course forgot the old thermostat. :( But, I decided to try the new one with just the two wires (red and white) connected in their marked locations, and the green disconnected. the heat did come up, but still not hot. New to the situation is a slight water hammer coming from the upstairs. The water pressure is reading at just under 10psi and the water temperature fluctuated between 160-170 Farenheit. Definitely thinkng I need to bleed the radiators again. At the least.

When I got home I took some terrible pictures of the old thermostat (T87f) to show the wall plate and thermostat attachment points, hopefully this will help you guys to visualize what I'm dealing with here. Please pardon my picture taking skills, I suck at it.
This is the wallplate and back of thermostat. Wall plate is as it faces away from the wall. I promise you there is no indication as to which wire goes where

The numbers on the 'stat... T87F 2873 3 9617

The back of the thermostat, showing where the screws come through to connect to the wallplate and some of the numbers I described in an earlier post.

closer shot of the wallplate showing where the screws connect. the wires were sandwiched in the middle. No Letters to signify R or W.

So, back to the boiler for a minute. NashuaTech said I needed 12psi, and I'm definitely lower than that. What are some possible causes that this would be low, and how would I go about adjusting this? And is the current water temperature the right range? I apologize for asking a million questions, but this is all brand new to me and I haven't been able to find much in the way to explain it.

I very much appreciate all of your ongoing help and advice, I definitely need it.

Re: Hot water system costly and cold


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