DN40 Insulation Jacket

This Greenlife DN40 insulation jacket fits over a DN40 (1 1/2in) closed circuit filter housing to cut heat loss and stop condensation building up on the casing. WrekinWater stocks it as a proper like-for-like replacement, shaped around the housing's union and valve fittings rather than a generic wrap. It's suited to anyone replacing a perished or missing jacket, or fitting insulation to a new DN40 housing for the first time.

Signs you need this part

• The jacket is torn, squashed flat or missing from the DN40 housing.
• Condensation appearing on the bare housing in a cooler plant room.
• The pipe run around the filter feels hot, indicating heat is escaping.
• A new or replacement DN40 housing has arrived without its jacket.

The DN40 housing sits directly in the heating flow, so without its jacket it radiates heat into the plant room and, in a colder space, can attract condensation that drips onto nearby surfaces or equipment. Because the jacket is shaped around the DN40 housing's union and valves, it insulates the awkward areas that a plain lagging wrap can't reach. Fitting it back doesn't change how the filter itself performs, but it stops ongoing heat loss and the damp issues that come with a bare housing.

WrekinWater is a family-run water treatment retailer in Bettisfield, Shropshire that has supported more than 50,000 customers over 15 years and is rated Excellent on Trustpilot. The DN40-specific jacket sold here is shaped to the housing rather than a universal cover.

How to fit it

1. Isolate the heating system before taking off any old, damaged jacket.
2. Wipe down the DN40 housing casing so the jacket fits against a clean, dry surface.
3. Fit the jacket around the housing, matching the cut-outs to the union and valve fittings.
4. Secure the straps or fastenings so the jacket sits snugly with no gaps.
5. Check the union is still reachable through the jacket for future servicing.
6. Return the system to service and check for condensation once it's back up to running temperature.