Pentax PM45-A Booster Pumps Automatic Control
The Pentax PM45-A automatic booster pump is a compact pump and controller in one, built to raise the pressure at taps, showers and washing points fed from a cold water tank or cistern. A Watertech Presscontrol unit is fitted to the pump outlet and pre-wired, so there is no separate pressure switch or pressure vessel to install. Open an outlet and the pump starts; close it and the pump stops a few seconds later.
The pump end is a Pentax peripheral pump: a brass impeller with many small radial blades spins inside a cast iron body, adding pressure as the water passes round the casing. This design gives high pressure at modest flow from a small 0.37 kW motor, which suits one outlet or a few used one at a time.
230v or 110v?
Both versions share the same pump, controller and connections. Choose the PM45-A 230v (022-402) for homes, flats and small commercial buildings on a normal single phase supply. The PM45-A 110v (022-403) is for building sites, welfare units and other places where tools and equipment run from a 110v transformer.
What the PM45-A can and cannot do
The pump reaches 40 metres of head (about 4 bar) with the outlet nearly closed, and holds 21 metres at 20 l/min. Pressure falls quickly as flow rises, so it is best for a single shower, a kitchen tap or a hose, rather than several bathrooms running together. For bigger demands, a multistage pump such as the Nocchi DHI keeps its pressure better at higher flows.
The Presscontrol also stops the pump if the water supply runs out, protecting it from running dry. Use it on clean water only; Pentax gives the pump a maximum operating pressure of 6 bar.
| Model | Supply | Motor output P2 (kW) | Max head (m) | Head at 10 l/min (m) | Head at 20 l/min (m) | Head at 30 l/min (m) | Max flow (l/min) | Inlet x outlet | Code |
|---|---|---|---|---|---|---|---|---|---|
| PM45-A 230v | 230v single phase | 0.37 | 40 | 30 | 21 | 13 | 40 | 1″ F x 1″ M | 022-402 |
| PM45-A 110v | 110v single phase | 0.37 | 40 | 30 | 21 | 13 | 40 | 1″ F x 1″ M | 022-403 |
Head figures are Pentax’s published performance for the PM 45A pump at 230v, which our curve for both versions follows. At 40 l/min the pump gives only about 5 metres, so plan on 30 l/min or less for useful pressure. Click through to either model for its full specification.
Showing all 2 results
40 l/min · 40 m · 230v
Pentax PM45-A 230v automatic booster pump with a pre-wired Watertech Presscontrol. Up to 40 l/min and 40 m head ...Read More£287.17 +VAT
40 l/min · 40 m · 110v
Pentax PM45-A 110v automatic booster pump for site supplies, with a pre-wired Watertech Presscontrol. Up to 40 l/min and ...Read More£325.81 +VAT
Where the PM45-A Works Best
The typical job is a home or small building with a cold water storage tank in the loft or a cupboard, where the taps or shower on the floor below get too little pressure because the tank sits only a little above them. Fit the PM45-A next to the tank outlet, below the water level so water flows into the pump, and it boosts every outlet on that supply. Our guide to how to increase water pressure covers the other causes of poor pressure worth ruling out first.
Under the UK water regulations you should not pump directly from the water main. Feed the PM45-A from a tank or cistern instead, as explained in what is a booster pump. It also suits washing points, small cleaning systems and garden watering from a rainwater or storage tank, as long as the water is clean and free of sand and grit.
On a building site, the 110v version can boost a welfare cabin supply from a bowser or storage tank on the same transformer as your other equipment. If you would rather fit your own controls to a 110v pump, the stainless steel Pentax Inox 80 110v is supplied as a bare pump.
Frequently Asked Questions
How does the PM45-A switch on and off?
The Watertech Presscontrol on the outlet senses pressure and flow. When you open a tap the pressure drops and the pump starts; when the tap closes and flow stops, the pump switches off after a short delay. Because it works on flow, there is no pressure vessel to check or recharge.
What happens if the tank runs dry?
The Presscontrol stops the pump when it detects a loss of water on the suction side and lights its red failure light. Once the tank has refilled, reset the controller with its restart button to bring the pump back into service. Watertech states that after a power cut the controller restarts by itself when power returns.
Is the PM45-A powerful enough for two showers?
Usually not at the same time. At 20 l/min the pump gives about 21 metres of head, which suits one shower or tap well, but at 30 l/min this falls to 13 metres and at 40 l/min to about 5 metres. For several outlets used together, compare duty points in our guide on how to choose the right booster pump.
Does the pump need to be below the water tank?
Yes. Install it so the water level in the tank is above the pump inlet, then fill the pump with water before the first start, as the controller needs a primed pump to work. Keep the suction pipe at least 1″ and as short as you can. If the highest outlet is several floors above the pump, call us first, as the controller’s restart pressure limits how high that outlet can be.
What size are the connections?
The pump inlet is a 1″ female thread and the Presscontrol outlet is a 1″ male thread, on both the 230v and 110v versions. Fit an isolating valve on each side so the unit can be removed for service without draining the system.
Not sure the PM45-A will give the pressure you need? Call AES Rewinds on 01252 515169 or email sales@aesrewinds.com with the number of outlets and the height from the tank to the highest one, and we will check it for you. You can also browse our full range of booster pumps.
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