For small unvented mains pressure water heaters (less than 15 litres capacity) the hotun dry trap tundish provides the perfect solution to compliantly resolve any prv discharge issues. Being small and compact with 2 standard connections, hotun can be installed in a matter of minutes and in the most confined places.

Connect the water heater’s pressure relief valve (PRV) through hotun and then direct to a local waste or foul drain, without odours being ventilating back into the building.

This provides an air break to drain with a safe and visible means of discharge, thereby allowing a compliant* connection.

hotun – not just a tundish

Product Features

  • 104mm tall x 57 mm wide
  • 1/2″ flat face tap connection on inlet
  • 22mm compression connection on outlet
  • Allows trickle** and full-bore discharges up to 12 litres/min
  • Temperature rated up to 100?C
  • Full WRAS approval
  • Air break to drain
  • Safe and visible means of discharge
  • 5 year warranty (T&C’s apply)
  • Available in black or white versions

The only WRAS approved, UK regulation compatible air break to drain tundish with inbuilt mechanical non-retun odour seal

Commonly called: odour seal tundish, dry trap tundish, trap tundish,?tundish valve, overflow tundish trap, dry odour seal tundish, sprung valve tundish,?non return tundish

hotun’s revolutionary, patented and simple, but visually appealing style, has many advantages over other more expensive and bulky options, fewer connections and no holes to drill through the external fabric of the building, the hotun will provide you with the most cost effective compliant solutions bar none!

  • To go to the alternative compliant options page, click here
  • To see all the regulations that need to be considered when making this type of connection, click here
  • To see some video clips of hotun discharge flow tests (trickle and full-bore), click here
  • To view the full operation, installation, service and warranty instructions, click here
  • For typical unvented installation types, click here

* It is compliant (when fitted in accordance with the installation instructions) with all necessary Water and Building Industry regulations, (in force wef Mar 2014)?provided that the waste and/or foul stack can be demonstrated to be able to withstand the effects of the expected temperatures being discharged. Please note, Polypropylene (PP) and High Density Polyethylene (HDPE) are generally accepted by building control to be used as suitable materials in this application. However, if in doubt, please contact your local building control for advice before installation.

** The spring/valve/diaphragm assembly is precisely engineered to hold the diaphragm shut under normal operating conditions (to prevent odours being ventilated back up from the foul waste pipes or drain), but still allow the valve to open with a minimal quantity of water in the upper chamber. We call this the trigger point and is set to release at between 5ml and 25ml of water. The upper chamber will hold 50ml of water before overflowing.

7 regulatory requirements – 1 simple solution