Amita

Amita non-return valves for pool and water circulation systems

Here you will find the Amita parts stocked at PoolParthub.com, currently centred on a compact non-return valve built for threaded pool pipework. It is one of those components that nobody thinks about until water starts running the wrong way through a system, and then it becomes the single most useful fitting in the plant room.

The valve is made from glass-fibre reinforced polyamide (PA GFR), carries a 6 bar pressure rating and uses a 1 inch female thread on a DN25 nominal bore, in black. Those few figures tell you almost everything you need to know before ordering, provided you check them against the pipework you already have.

What a non-return valve actually does

A non-return valve — also called a check valve — allows water to pass in one direction only. In a swimming pool installation that has several practical uses:

• Protecting the pump: it stops the column of water in the pressure line draining back through the pump housing and basket every time the pump stops.
• Keeping the pump primed: with the suction side held full, restarting is faster and the pump is less likely to run dry.
• Separating circuits: on a system with a heat pump, solar matting, an automatic top-up or a chemical dosing line, a check valve keeps flow from one branch out of another.
• Dosing safety: it prevents treated or concentrated water being pushed back towards a dosing pump or an injection point.
• Back-siphonage: on a mains top-up line it forms part of keeping pool water out of the feed pipework.

Because the valve is a moving part sitting permanently in treated water, it is also a wear item. It is normal for a check valve to be replaced several times over the life of a pump or filter.

Checking the size before you order

DN25 and 1 inch describe the same nominal size, and in pool plumbing that usually sits alongside 32 mm solvent-weld pipe by way of a threaded adaptor. Before ordering, it is worth confirming a few things on the existing installation:

• Thread gender: this valve has a female thread, so it needs a male-threaded adaptor, union or tail on each side.
• Gewindestandard: compare the fitting you are replacing rather than assuming; a thread gauge or a known-good adaptor screwed in by hand is the quickest check.
• Rohrdurchmesser: measure the outside diameter of the rigid pipe, or the inside diameter of a flexible hose, and match it to the adaptor rather than to the valve.
• Betriebsdruck: a 6 bar rating is generous for domestic pool circulation, but note that it is a maximum and not a target.
• Strömungsrichtung: fit the valve so the arrow or marking on the body follows the direction of flow, otherwise it will simply shut the line.

Polyamide reinforced with glass fibre is chosen for this kind of fitting because it is dimensionally stable and does not corrode in chlorinated water. It does, however, mean the body should be tightened by hand and then only gently with a tool. Over-tightening a plastic thread is the most common way these fittings fail.

Signs that a check valve needs replacing

Diagnosis is usually straightforward. If the pump basket empties shortly after the pump stops, or if water audibly drains back down the pressure line, the valve is no longer seating. Scale deposits, grit from a sand filter, leaf fragments and hardened sealing surfaces all stop the internal element closing fully. A weeping thread or a hairline split in the body is a replacement rather than a repair.

When fitting, use PTFE tape or a thread sealant suitable for plastic threads, do not use jointing compounds that attack polyamide, and support the pipework so the valve is not carrying mechanical load. Mounting the valve where it can be reached — rather than buried behind a filter — makes future checks far easier.

Amita at PoolParthub.com

Here we list the Amita items we hold for pool circulation plumbing, at present the DN25 non-return valve with a 1 inch female thread, 6 bar rating and black PA GFR body. It is a straight functional replacement for a failed or missing check valve on a pump line, a top-up feed or a dosing branch.

We stock it because it is a small part with a large consequence: a non-seating valve means lost prime, repeated manual priming and avoidable load on the pump. Keeping common sizes available alongside adaptors, unions and seals means a circulation system can be put back in service without re-plumbing a whole section.