The WaterBoost Coffin range
The low-profile water boosting solution for lofts, eaves, under-floor voids and any installation where height is restricted.
Up to 80 l/min at 3 bar pressure — seven models, four tank sizes, two pump tiers, all variable speed.
Boosting water pressure in a property with a loft, eaves space or under-floor void as the only available install location used to mean a serious compromise. Standard upright booster tanks simply don’t fit, and the alternative — pumping water from a remote storage location — adds cost and reduces performance.
The WaterBoost Coffin range is engineered specifically for these installations. Its low-profile horizontal “coffin” tank fits where upright systems can’t — under floors, in eaves, low lofts, and any space with a height restriction — while still delivering full whole-house boost performance from a renowned DAB Esyline variable-speed pump.
Our Managing Director, Glen Denny, walks through what makes the Coffin range different and how to choose the right configuration.
What is a Coffin booster and how does it work?
A Coffin booster is a low-profile water boosting system built around a horizontal “coffin-shaped” Polytank rather than the upright vessel used in conventional whole-house boosters. The tank fills from the mains via a By-law 30 kit and 1/2″ ball valve (both pre-fitted), and a DAB Esyline variable-speed pump draws from the tank to deliver boosted water on demand.
The horizontal form factor means the system can be installed in spaces where height is the binding constraint — lofts with low headroom, under-floor voids, eaves cupboards, garage corners, and similar locations where an upright tank simply will not fit.
Why choose a Coffin booster?
Horizontal tank profile designed for height-restricted installs — lofts, eaves, under-floor voids, garages.
DAB Esyline Mini3 or Esybox pumps — match output to demand for lower running costs and longer pump life.
Polytank-supplied vessel with pre-fitted By-law 30 kit and 1/2″ ball valve — compliant out of the box.
All interconnecting pipes included. Prebuilt and ready to use — minimal install time, minimal labour cost.
Which Coffin model do you need?
Coffin sizing combines two decisions — tank size (how much stored water you need) and pump tier (how much flow you need to push). Use this guide to narrow down:
1–2 bathrooms
Compact properties or smaller homes where install space is limited and demand is moderate.
200L tank · Mini3 or POP pump2–3 bathrooms
Standard family homes wanting reliable whole-house boost with longer run capacity.
320L tank · Mini3 or Esybox pump3+ bathrooms
Larger properties with higher simultaneous demand and the need for sustained high flow.
450L tank · Mini3 or Esybox pumpENTRY Cost-effective compact boost
STANDARD DAB Esybox Mini3 — proven workhorse
PREMIUM DAB Esybox — higher flow performance
Not sure which pump tier you need? Esybox Mini3 covers most domestic installs. Step up to the full Esybox if multiple bathrooms run in genuine simultaneous use, or if you need a bit more headroom at the tap.
Designed for fast, simple installation
Every Coffin system arrives prebuilt and ready to install. The Polytank vessel is supplied with the By-law 30 kit and 1/2″ ball valve already fitted, and all the interconnecting pipework between tank and pump is in the box. There is no on-site assembly required beyond positioning the unit, connecting mains in and boosted out, and powering up.
For installers, this means a faster job and a lower labour cost. For homeowners, it means a lower overall install bill and a system that is up and running the same day.
Most Coffin installs complete in a single visit. Two water connections, one electrical supply, done.
Why variable speed matters
Every model in the Coffin range — including the entry-level POP — uses a variable-speed pump. This matters for three reasons:
Lower running costs. The pump matches its output to actual demand rather than running at full output every time it cycles. Over a year, this makes a meaningful difference to electricity use compared with a fixed-speed equivalent.
Longer pump life. Variable-speed pumps run cooler, with fewer hard starts and stops. Bearings last longer, seals last longer, and pump replacement intervals stretch out.
Stable pressure at the tap. Output ramps up and down smoothly as demand changes, so showers and taps maintain consistent pressure even when other outlets are in use.
Coffin vs upright booster — which fits your install?
If your install location has full ceiling height available, a conventional upright booster (like our WaterBoost Slimline range) will give you the same performance in a smaller footprint. Choose Coffin when the install location has a height restriction — typical scenarios are:
Lofts and roof spaces with low headroom or sloped ceilings.
Under-floor voids in raised-floor properties or where access is via a hatch.
Eaves cupboards where upright tanks would foul the ceiling slope.
Garage corners where upright units would block doors or shelving.
Outhouse fits where the existing structure can’t take a tall upright unit.
If the only available space is height-restricted, Coffin is the answer. If height isn’t the constraint, the Slimline range will usually be a more compact and cost-effective choice.
Need help choosing the right Coffin model?
Tell us your install location, available headroom, and the number of bathrooms — our technical team will recommend the right tank size and pump tier.
Get sizing help →