---
product_id: 114786787
title: "GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray"
brand: "flextrol"
price: "37.65 OMR"
currency: OMR
in_stock: true
reviews_count: 8
url: https://www.desertcart.com.om/products/114786787-gui37-hydronic-expansion-tank-for-heating-system-carbon-steel-grey
store_origin: OM
region: Oman
---

# Max Temp 210°F 2.1 Gal Capacity NSF61 Certified GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray

**Brand:** flextrol
**Price:** 37.65 OMR
**Availability:** ✅ In Stock

## Summary

> 🔥 Elevate Your Heating Game with Unmatched Safety!

## Quick Answers

- **What is this?** GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray by flextrol
- **How much does it cost?** 37.65 OMR with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.om](https://www.desertcart.com.om/products/114786787-gui37-hydronic-expansion-tank-for-heating-system-carbon-steel-grey)

## Best For

- flextrol enthusiasts

## Why This Product

- Trusted flextrol brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **🏗️ Built to Last:** Solid carbon steel construction with a premium polypropylene liner.
- • **🔒 Unmatched Safety:** Protects your heating systems from dangerous pressure build-up.
- • **🔄 Extended Lifespan:** Low profile design reduces diaphragm stretching, enhancing durability.
- • **💧 Leak-Free Assurance:** Factory leak tested for peace of mind.
- • **🌡️ High-Performance Specs:** Handles max operating pressure of 75 PSI and temperatures up to 210°F.

## Overview

The GUI37 Hydronic Expansion Tank is a robust solution for your heating system, featuring a 2.1-gallon capacity and built from solid carbon steel. It is designed to prevent pressure build-up and potential leaks, ensuring a safe and efficient operation. With NSF61 certification and a maximum operating pressure of 75 PSI, this tank is engineered for high performance and longevity.

## Description

GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray

## Features

- Protects Your Heating Systems; Prevents Dangerous Pressure Build up; Eliminates Potential Leak Path
- Features a Solid Carbon Steel Construction with an Exclusive Polypropylene Liner, MIG Welding, SBR Rubber Diaphragm, and External Baked Epoxy-Polyester Coating for Superior Performance
- Each Tank is Factory Leak Tested and NSF61 Certified
- Max Operating Pressure 75 PSI; Temperature 210°F
- Low Profile Tank Design with Full Membrane Depth Eliminates Stretching of Diaphragm, Providing Increased Life Cycle

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Brand | HIGHCRAFT |
| Color | Gray |
| Heat Output | 2.1 Gallons |
| Maximum Operating Pressure | 150 Pound per Square Inch |
| Manufacturer | Highcraft |
| Part Number | GUI37 |
| Item Weight | 4.6 pounds |
| Product Dimensions | 9 x 9 x 13 inches |
| Item model number | GUI37 |
| Size | 2.1 Gallons |
| Item Package Quantity | 1 |
| Number of Handles | 1 |
| Included Components | Hydronic Expansion Tank |
| Batteries Included? | No |
| Batteries Required? | No |
| Warranty Description | 1 Year |

## Images

![GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray - Image 1](https://m.media-amazon.com/images/I/61G80gDJ6CL.jpg)
![GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray - Image 2](https://m.media-amazon.com/images/I/61cSmLazatL.jpg)
![GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray - Image 3](https://m.media-amazon.com/images/I/61lDE2jPagL.jpg)
![GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray - Image 4](https://m.media-amazon.com/images/I/71qZ200RjML.jpg)
![GUI37 Hydronic Expansion Tank for Heating System Carbon Steel Grey Holds 2.1 Gal, 2.1 Gallons, Gray - Image 5](https://m.media-amazon.com/images/I/71sZM5ZaJVL.jpg)

## Available Options

This product comes in different **Size** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ 5.0 out of 5 stars







  
  
    What can I say?  It's a pressure tank.
  

*by K***. on Reviewed in the United States on February 23, 2020*

I picked this up when building the manifold for my floor heating system.  It appears to be well built with clean threads on the attachment point.  It is now installed and helping relieve pressure build up in my system.  I'm running about 25lbs of pressure on the system and it appears to be handling it with no problem.

### ⭐ 1.0 out of 5 stars







  
  
    junk
  

*by A***R on Reviewed in the United States on September 16, 2020*

The item description states 3/4 inch fitting but it is only 1/2 inch. I like to rely on Amazom to provide accurate information. This error caused me to take time during Covid-19 to go to the hardware store for a reducer. The cost was not the issue. The effort involved was. The product was well made and works as it should. No complaints there.UPDATE: failed after just a few monthe...filled with water and became useless

### ⭐⭐⭐⭐ 4.0 out of 5 stars







  
  
    Get a pressure gauge first.
  

*by B***B on Reviewed in the United States on February 28, 2021*

They are precharged to 12psi and I installed upside down (threads down) and included a threaded shutoff.  I installed without having a gauge for my water.  My system's water pressure turned out to vary between 38 and 50psi.  50psi is only 10psi below this tank's maximum.  It's on a Solar hot water system.  I had to remove it after turning the valve off and it was like a water cannon.  Pretty exciting.  Charged to 40psi and reinstalled.  I give it 4 stars because of its 60psi rating.  My 400 year old boiler plumber installs upside down because they last longer and more capacity.  The ball valve has already saved me from refilling the system once.  I'm still not exactly sure what pressure I should have charged it to given my range of water pressures.  I went with the lower end so as to not stress the bladder more.

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**Shop now:** [https://www.desertcart.com.om/products/114786787-gui37-hydronic-expansion-tank-for-heating-system-carbon-steel-grey](https://www.desertcart.com.om/products/114786787-gui37-hydronic-expansion-tank-for-heating-system-carbon-steel-grey)

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*Product available on Desertcart Oman*
*Store origin: OM*
*Last updated: 2026-01-24*