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Hydrotherm Age, Manuals, Parts Lists, Wiring Diagrams

  • POST a QUESTION or COMMENT about where to find Hydrotherm heating boiler installation and service or maintenance manuals and guides

For Hydrotherm heating boilers this page provides free downloadable manuals, wiring diagrams and repair guides.

We discuss how to find or estimage the age of a Hydrotherm boiler and discuss, in this case, the lack of a good Hydotherm boiler data tag serial number decoder. Instead we rely on context and surrounding clues to get the age of the boiler.

This article series gives free downloadable manuals for Air Conditioners, Boilers, Furnaces, Heat Pumps. Here we provide free downloadable copies of installation and service manuals for heating, heat pump, and air conditioning equipment, or contact information for the manufacturers who can provide that information for nearly all major brands of HVAC equipment.

Page top photo of a HydroTherm Model MR420 gas boiler data tag provided by reader Janna.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Hydrotherm Boilers: Age, Parts, Manuals, Contact

Example parts list for window A/C unit from Sears Here we provide manufacturer contact information and direct links to free downloadable installation, service, and users manuals for Hydrotherm boilers.

Hydrotherm boilers (an "Advanced Thermal Hydronics" company, now owned by Mestek, www.mestek.com), encode the age in some but not all of the product serial numbers, depending on the Hydrotherm model and age.

Article Contents

Contact Hydrotherm Boiler Company

Age Decoder for Hydrotherm Boilers - Company H

Hydrotherm Boiler Data Tag (C) InspectApedia.com reader JannaUnfortunately, unlike some other boiler and furnace brands, Hydrotherm boiler age is not regularly or easily encoded in or decoded from the boiler serial number on the HydroTherm data tag.

However if you provide a photo of your boiler's data tag and of the boiler itself, using the tips

at BOILER / FURNACE AGE GUESSER we'll give just below we may be able to make a more-specific guess at your boiler's age.

History of the Hydrotherm Boiler Company

Boiler Age Determination from Surronding Contex & Clues

Here are our tips for making an intelligent guess at hvac equipment age when there is no direct age decoder available.

When there is no direct age decoder for a boiler based on its serial number we look at the surrounding and contextual clues including the items given below.

Hydrotherm HI-125 Series Boiler data tag (C) InspectApedia.com Soto

Hydrotherm & ATG Advanced Thermal Hydronics Boiler Manual Downloads

Hydrotherm HC-100 boiler (C) InspectApedia.com Mario

Hydrotherm HI-125B-Propane Boiler Data Tag (C) InspectApedia.com

[Click to enlarge any image]

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-12-01 by Mario - Where can i get a thermostat for a Hydrotherm HC-100?

Hi, Where can i get a thermostat for a Hydrotherm HC-100 old Boiler - Must be compatible with 24V DC (not AC)

Oh, by the way - My Hydrotherm HC-100 Boiler was installed in 1967 and it is still running like a champ (AMAZING) but i need a new Thermostat, it must be 24V DC so that it can open the 3 zone valves. Thanks for any imput !

My Hydrotherm HC-100 with 3 electro zone valves

Hydrotherm HC-100 boiler (C) InspectApedia.com Mario

On 2022-12-02 by InspectApedia (mod) - Hydrotherm HC-100 Boiler manual needed

@Mario,

In our list of available manual downloads above on this page, see this:

HYDROTHERM HC-D BOILER MANUAL [PDF] also helpful re: the Hydrotherm HC-100 boiler

You can also contact the company directly at

The Hydrotherm Corp. 260 N Elm St. Westfield, MA 01085 USA Tel: 413-564-5515

On 2022-12-02 by Mario

@InspectApedia ,
Downloaded the Hydrotherm HC-D manual as per your suggestion. Will contact the Company as early as possible to inquire about a suitable thermostat. Thanks for the info !

On 2022-11-25 by Falcon

Have a hydro-therm r-210 boiler. Do I set it to auto or manual?

On 2022-11-25 by InspectApedia (Editor) - hydro-therm r-210 boiler control settings

@Falcon,

I want to help but don't understand if you're asking about a control on your boiler (see the manual below) or about how to set your thermostat.

Normally if you've got hot water heat your thermostat will be set on AUTO

If you're asking about a Hydrotherm boiler control setting I need to understand what you're trying to adjust.

The manual for your Hydrotherm R-series boiler, if you don't have it, can be downloaded free at

HYDROTHERM R-SERIES BOILER MANUAL [PDF] - RC-2 installation operation maintenance manual for Hydrotherm Gas-Fired Water Cast Iron Boilers 180,000 to 300,000 Btuh Input Standing Pilot, Intermittent Pilot & Vent Damper

On 2022-11-04 by Edith - proper pressure for Hydrotherm boiler?

I like to know at what the PSI meter should read when in heating service on the Hydrotherm on a 2 floor Home heating system

On 2022-11-04 by InspectApedia-911 (mod) - how to read the boiler pressure gauge

@Edith,

Sure, glad to help.

Let's sort out a few terms and numbers.

When your heat is by a forced hot water boiler system (hydronic heating), for a typical two story building, the water pressure in the boiler and piping will be at 12 psi when the boiler is cold, and will get as high as into the high twenties, perhaps 28 or even 29 psi when the boiler is at full or hottest operating temperature - up to around 180 to 200 degF.

If the boiler gets hotter than 200F the pressure will exceed 30 psi and the boilers pressure/temperature relief valve will open to spill hot water and relieve pressure - a safety device.

What you call the "PSI meter" I'd call the boiler pressure gauge.

PLEASE take a look at this article:

GAUGES, HYDRONIC BOILER

where we explain how to read the boiler pressure gauge and what pressures mean, and where we offer boiler pressure gauge diagnostics.

Question: Hydrotherm HI-125 Limit Relay stopped working - need wiring diagram

Hydrotherm HI-125 boiler tag - ca 1985 (C) InspectApedia.com WB

Photo: Hydrotherm HI-125 Boiler Data tag courtesy of IAP Reader William Balough by private email 2022-09-21

I am looking at a hydro therm boiler and the temp limit relay for some reason was working properly now it's not.

Is there a way to get the proper wiring diagram to help me figure out where the Short is.

We traced every wire, no evidence of anything burned up. When we initially fired up the boiler it was working fine and then randomly cut out but the blower was still running.

Checked all the voltages and the only place we lost voltage was the thermal relay on the bottom of the boiler going from where the thermostat wires came down and then out to the stat on the boiler itself that sets the internal water temp.

So we tried to jumper it and got an odd buzzing/clicking noise and the. Blower went into like a safety low speed but when we took the jumper off it went back to blowing high speed but still had no spark igniter

Microtemp G4AM0600 TF192C APM on a Hydrotherm boiler (C) InspectApedia.com Balough

Here is the relay that we think is failing: Microtemp G4AM0600 TF192C APM

Moderator reply: where to find boiler limit control instructions & wiring diagrams - Microtemp Thermal Fuse Replacement Instructions

Above on this page We have manuals for HydroTherm boilers but not your specific model - I'm still researching that.

(We added your photo there (keeping you anonymous) and will post this discussion to see if anyone else can help).

Meanwhile, the limit control is almost certainly not a unique Hydrotherm part. 

It sounds as if there is a failed relay or a jammed electric motor.

Give me a photo of and the model number and band of the limit control and we can probably find its wiring guide. 

Also see the instruction manuals and wiring diagrams for boiler limit controls at these pages where we may already have your limit control instructions:

AQUASTAT SELECTION GUIDE - complete list

LIMIT CONTROL, SINGLE

LIMIT SWITCH, BOILER

Some Starting Tests for your Hydrotherm Boiler

  1. Confirm that power is on to the boiler
  2. Confirm that the boiler temperature is well below the upper limit on the limit control - or typically below 180F - say at 150 or cooler.
  3. Confirm that you have line voltage at L1 & L2
  4. Disconnect the thermostat wires from the T - T terminals and then connect a jumper wire between those two terminals - that's the same as turning up the thermostat but eliminates the whole thermostat circuit from the equation
  5. Check for line voltage (120VAC) at Terminals 2 and 3 - the Circulator Terminals

    If you see no voltage at the circulator terminals then the control board relay may have failed GA

Watch out: if you are not familiar with safe electrical wiring and basic electrical testing, leave this procedure to your trained service professional - else you could be shocked or killed.

Following up:

That Microtemp G4AM0600 TF192C APM is probably a thermal fuse - here is

Microtemp's THERMAL FUSE CATALOG [PDF] - retrieved 2022/09/21 original source: https://climate.emerson.com/documents/data-sheets-bulletins-microtemp-thermal-fuses-product-information-application-notes-en-us-4107344.pdf

Excerpt:

Operating Principle

The active trigger mechanism of the thermal fuse is an exclusively formulated, electrically nonconductive pellet.

Under normal operating temperatures, the solid pellet holds spring loaded contacts closed.

When a predetermined temperature is reached, the pellet melts, allowing the compression spring to relax. The trip spring then slides the contact away
from the lead and the circuit is opened.

After the thermal fuse opens a circuit, the fuse needs to be replaced.

This replacement procedure must include correction of the fault condition before the product is operated again.

So you want to check for a seized motor or shorted wire or control board after replacing the fuse and before turning the system back on - else the new thermal fuse may simply blow again.

(Or buy a couple of them) <g>

Reader follow-up: relay burned up, back fed and fried the control board.

Sure as s**t, the relay burned up causing it to back feed and fried the board.

Thank you for all your help- William Balough 2022/09/22

Question: manual for the Hydrotherm R210-C

I need a manual for the Hydrotherm R210-C - 2022-09-01

Moderator reply:

This Hydrotherm Manual, found at InspectApedia applies to your model

HYDROTHERM R-SERIES BOILER MANUAL [PDF] RC-2 / RC2 installation operation maintenance manual

also see

HYDROTHERM MODEL R SERIES INSTALLATION, OPERATION & MAINTENANCE MANUAL & REPLACEMENT PARTS LIST [PDF] - found as a live link above on this page

Often the -A manual will also pretend to be C or other models and may even cite them as included in the "A" manual with specific if minor differences.

So did you take a look at the a model manual to see if it also covers your C- model Hydrotherm R210

Question: HydroTherm gas boiler identification & replacement: Calgary, Alberta

HydroTherm gas boiler data tag - partial - Carl Palomaki (C) InspectApedia.com

Help me age this unit? When about it was made! Snd how much for an energy efficient replacement to be shipped to Calgary, Alberta! My gas fitter will install…
Kind regards,
Carl
cpalomaki@ivloud.com - 2022/03/07

This Q&A were posted originally at HOW TO REALLY CUT HOME HEATING COSTS

Moderator reply:

@Carl Palomaki,

Unfortunately your photo of the gas boiler data tag cut off the bottom but I think I see a sliver of text identifying it as a Hydrotherm gas boiler.

So please see details including age decoding for HydroTherm boilers found above on this page.

Sorry, but we cannot provide the replacement Hydrotherm boiler sale/purchase that you asked about.

We do not sell anything. No products, no services.

InspectAPedia.com provides building and environmental diagnostic and repair information. 

In order to absolutely assure our readers that we write and report without bias we do not sell any products nor do we have any business or financial relationships that could create such conflicts of interest.

Question: Where to find the manual for my HydroTherm R-210B boiler

I have a hydrotherm low pressure boiler model r-210b serial # rb 4880..I can’t find any info on this model..everything I find is on the r-210c..I’d like to find schematics on this unit or anything really. - Scott ODonnell 2021/12/15

HydroTherm gas boiler identification and age data tag (C) InspecdtApedia.com ODonnell

Moderator reply:

Scott, this Hydrotherm Manual, found at InspectApedia applies to your model

Often the -A manual will also pretend to be C or other models and may even cite them as included in the "A" manual with specific if minor differences.

So did you take a look at the a model manual to see if it also covers your C- model Hydrotherm R210

 

On 2021-04-28 by Jeff Miller Willamalane Park and Rec. - need KN-20 manifold gasket,

Looking for a quote on KN-20 manifold gasket, see Boiler tag photo for info

[Click to enlarge any image]


On 2021-04-28 by (mod) - where to buy a replacement manifold gasket for Hydrotherm boiler

Hydrothermo boiler gasket for KN20 boiler at InspectApedia.com@Jeff Miller Willamalane Park and Rec., Sorry, but we cannot provide the product that you asked about.

We do not sell anything. No products, no services.

InspectAPedia.com provides building and environmental diagnostic and repair information.

In order to absolutely assure our readers that we write and report without bias we do not sell any products nor do we have any business or financial relationships that could create such conflicts of interest.

InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.

A brief summary about InspectAPedia.com can be read at ABOUT InspectApedia.com - https://inspectapedia.com/Admin/About_InspectApedia.php

However, there are numerous vendors of gaskets that fit your Hydrotherm KN20 boiler - I've seen prices from about $3.50 to $22. U.S.D. for gaskets like the one below.

Let's start by dipping into the IO manual for your Hydrotherm KN20 - to be sure you've got the exact part number right.

Continuing: if you don't already have the manual for your KN-20 you can download it as a free PDF from links on the page above - or try

HYDROTHERM KN-SERIES GAS BOILER IO MANUAL [PDF] (2014) Installation & Operation Instructions


HYDROTHERM KN-SERIES GAS BOILER CONTROLS MANUAL [PDF] this is the control IO manual for KN boilers

On 2021-01-07 by Mike - retrofit an older HCD2-501 Hydro-Therm boiler with Spill & Rollout switch units ?

Is there an aftermarket kit to retrofit an older HCD2-501 Hydro-Therm boiler with Spill & Rollout switch units ?

On 2021-01-07 by (mod) - add-on or retrofit flue gas spill switch kits for gas fueled heating equipment

Mike

There are retrofit flue gas spill switch kits that work on a variety of gas fired heating equipment when properly located and installed. An example is the Field Controls SSK-1 described by vendor literature as follows:

Kit form of GSK-3 or GSK-4 generally used on millivolt water heaters.

Can also be used with 24 VAC gas furnaces or boilers. Kit includes (2) GSK style Thermal Safety Switches, (1) 12-gauge Jumper Wire and (1) 6 ft. length 12-gauge lead wire.

SSK-3 switches not supplied with switch enclosures. TCA-1 or TCA-2 Thermocouple Adapter required for 30 millivolt applications.

Before and after adding this safety control on existing appliances, an installation inspection in accordance with the National Fuel Gas Code 54, Z223.1 Appendix H should be performed and a combustion analysis is recommended to determine the operating condition of the appliance.

Your installer will check to assure that this or a similar device can work safely with your HydroTherm boiler.

Also see this

FIELD-SSK1 FLUE GAS SPILL SWITCH INSTRUCTIONS [PDF]

And see details at

FLUE GAS SWITCH INSTALLATION & WIRING

FLUE GAS SPILL SWITCH SOURCES & SELECTION

On 2020-12-12 by Tracey garcia - wha'ts the date of this boiler?

I was wondering if u could tell me the date of this boiler. Model hc100 serial # ox6385. Im trying to find a relay switch. Would i be able to call the co and give them this info and order one from them? Picture attached

On 2020-12-07 by Anonymous - what is the manufacturing date of R300B Cerial No. CHD1006 Boiler

what is the manufacturing date of R300B Cerial No. CHD1006 Boiler

On 2020-12-13 - by (mod) -

Most likely you can order the part you need from the local plumbing and heating supplier or if you call the manufacturer they can tell you who has the part that you need if it's Unique to your heater.

On 2020-05-25 by jmacduff - need pilot assembly for HC 145C boiler

looking for pilot assembly for Hydro Therm HC-145C

On 2020-05-26 - by (mod) - where to buy pilot assembly for Hydro Therm HC-145C

JM

Sorry, but we cannot provide the product you asked about. We do not sell anything. No products, no services. InspectAPedia.com provides building and environmental diagnostic and repair information.

In order to absolutely assure our readers that we write and report without bias we have no business nor financial connection with any manufacturer or service provider discussed at our website.

A brief summary about InspectAPedia.com can be read at https://inspectapedia.com/About_Us.htm

However
Numerous suppliers sell HydroTherm boiler parts including the pilot assembly, such as https://controlscentral.com/ illustrated above.


Question: Hydrotherm Model GW743 Serial No. C-1361 Age?

2020/05/08 rowergirl@rogers.com said:

We have a hydrotherm boiler. Serial number is C-1361 model number GW743. Any idea how old it is and do we wait until it finally stops working to replace it? And do u reccommend a dual boiler water heater? Thanks

This Q&A were posted originally at AGE of HEATER BOILER FURNACE FAQs

Moderator reply: clues for obtaining a boiler age when it's not neatly encoded on the data tag

Rower

The best info we have on decoding Hydrotherm boiler serial numbers and more details about Hydrotherm boilers as well as contact info and manual downloads is above on this page.

Hydrotherm boilers (an "Advanced Thermal Hydronics" company, now owned by Mestek, www.mestek.com), encode the age in some but not all of the product serial numbers, depending on the Hydrotherm model and age.

By calling-in the serial number the company can often give you the date:

USA 413 564 5515


On 2019-09-19 by Janna - I need to know the age of this commercial broiler!

Hydrotherm Boiler Data Tag (C) InspectApedia.com reader JannaI need to know the age of this commercial broiler!
Hydrotherm inc.
Model MR420

I have a HydroTherm model HC-100 and the serial number OX-8204

On 2018-10-19 - by (mod) -

Melissa: I'll look for and post a link to the HydroTherm manual for your unit
at

inspectapedia.com/heat/HVAC-Manuals-Air-Conditioners-Boiler-Furnaces-F-I.php#Hydrotherm

you can also contact the company directly at

The Hydrotherm Corp. 260 N Elm St. Westfield, MA 01085 USA Tel: 413-564-5515

On 2019-09-19 - by (mod) -

Hi Janna

Help me out by typing the serial number - I THINK it reads CA11288 but I'm not sure.

Checking out our article: HVAC MANUALS, PARTS LISTS, WIRING DIAGRAMS - where I'm sorry to say that Hydrotherm, now owned by Mestek, www.mestek.com, has chosen not to give out ANY public information on how to decode their serial numbers.

However by calling in the serial number the company can often give you the date: USA 413 564 5515 or Canada: 905 672 2991

Contact:

The Hydrotherm Corp. 260 N Elm St. Westfield, MA 01085 USA Tel: 413-564-5515

Hydrotherm Canada 5211 Creekbank Rd. Mississauga, ON L4W 1R3 Canada Tel: (905) 625-2991 Fax: (905) 625-6610

Website: http://www.hydrotherm.com

On 2018-03-14 by John Mullen - Hydrotherm serial number ra 1535 model r180 B trying to find the age

Hydrotherm serial number ra 1535 model r180 B trying to find the age

On 2018-03-15 - by (mod) -

John

You will need to call the company. See details at

https://inspectapedia.com/heat/Hydrotherm-Age-Manuals-Contact.php

On 2017-04-20 by Ron - Hydrotherm gas boiler age needed

Hydrotherm gas boiler age needed serial number HNA-3191

On 2017-04-21 by (mod) re: decoding the age of a Hydrotherm boiler from the serial number

Ron

Hydrotherm boilers (now owned by Mestek, www.mestek.com) encode the age in some but not all of the product serial numbers, depending on the Hydrotherm model and age.

By calling-in the serial number the company can often give you the date: USA 413 564 5515 or Canada: 905 672 2991

Hydrotherm as well as Carson Dunlop's Technical Reference Guide (cited in the home page for this topic at AGE of HEATERS, BOILERS, FURNACES) note that the date is often stamped at the bottom of the Rating Plate on the boiler.

But if don't see an obvious 2 or 4 digit year code, then you'd need to call the manufacturer. We include some example Hydrotherm boiler age decodings below.

With Hydrotherm's newer serial numbers in the format AA-1234-5678 the year is in positions 1234.

For SOME older Hydrotherm boilers the age follows AAA-1234 where I think digits 12 encode the week and digits 34 encode the year.
Your HNA-3191 then decodes to 1991

For OTHER older Hydrotherm boilers the age is encoded in the serial number in the first two or three positions, example:

Serial No. 8228474 with no alphabetic characters encodes the year in the first to digits as 82 = 1982

M-150 serial 08607162 encodes the year in the 2nd and 3rd digits so 086 = 1986
A-150 serial 8506226 encodes the year in the first two digits so the year = 1985

Adding to this Hydrotherm boiler hullabaloo, on other newer Hydrotherm models the year is encoded as a capitalized alphabetic character at the end of the alphabetic part of the serial number,
e.g.
OR-140 serial SCSC -1153 the last "C" decodes to 1992 and a "D" in a similar position will decode to 1993

You can also contract the company directly at
The Hydrotherm Corp.
260 N Elm St.
Westfield, MA 01085 USA
413-564-5515

or
Hydrotherm Canada
5211 Creekbank Rd.
Mississauga, ON L4W 1R3
Canada
Phone: (905) 625-2991
Fax: (905) 625-6610
Website: http://www.hydrotherm.com

See HYDROTHERM Boilers

On 2017-03-19 by Tonya Thompson

I am trying to find the age of my parents furnace. It is a Hydro Therm Model HC 125, Serial # Or22088.

On 2017-03-19 by (mod) re: Decode the age of a Hydrotherm Boiler HC125

Since the year of manufacture is often coated in the serial number, I would guess 1988

...

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