By Luke Parry | Area Sales Manager - DiversiTech International
So the hot topic right now is what pipework insulation should be used outdoors.
It's been on the horizon for a while, but for years there has been no cost-effective alternative to the standard indoor class '0' insulation. That's no longer the case, but let me explain.
For aircon installers, it has become normality to use standard class '0' inslation on pipe work outdoors. Unprotected, uncovered, exposed to the elements. However, when the rapid increase of air source heat pump installations kicked off, there was a lack of standard 'install norms' in this new space. So simple questions arose, like 'what lagging should be used on the outdoor pipework?'
As with an air conditioning system, the efficiency or an air source heat pump relies heavily on heat retention in the pipework. However, us humans have a very low tolerance of any imperfections in our heating system, compared to a degress or two of difference in our air conditioning. To cut a long story short, the exact type of lagging to be used on an ASHP was thoroughly investigated.
The findings?
- Using standard class '0' (now Euroclass 'B') outdoors, without any protection, is unacceptable due to the deterioration in effectiveness over time. Lack of UV protection leads to perishing (drying & cracking), softness of the material makes it attractive for birds to peck and use in nests, and the combination of these two factors means that water enters holes and cracks and takes the effectiveness of the insulation down significantly.
- When there are insulation gaps anywhere on the outdoor pipe run, it leads to heat loss of up to 10% in the system. (That's on a short domestic pipe run!) Gaps in the insulation include unlagged fittings, such as ball valves, and connections to the unit itself. Another typical area of huge heat loss is where pipework goes through a wall and isn't correctly lagged.
- The standard grey plumbing insulation is neither weatherproof or waterproof, and will absorb water, rendering it completely useless. (It is also not UV stable).
So, what is the new best practice?
- Euroclass B, with a weatherproof PVC coating is the only insulation suitable for outdoor, unprotected applications. This is UV stable, and will not allow any form of water ingess and is tough enough to resist animals.
- Standard Euroclass B without a PVC coating can be used outdoors, but must be protected by plastic trunking or fully under cover and sheltered from rain/sunlight.
- All joints in outdoor insulation should be sealed with insulation tape or adhesive, and fittings should be entirely covered.
- Air source heat pumps require 19mm thick insulation on all outdoor pipework to be compatible with building regulations.
Increasing investment into the manufacturing of PVC-coated insulation has brought both the availability and the price-point to a level which makes it an attractive option compared to the combination of standard insulation with plastic trunking. We would recommend you trial this product, now available in all relevant sizes from Greenmill.
Whatever the application, remember that future efficiency of the system depends on the ongoing heat retention within the pipework. Quit blagging, use the right lagging!
