The product known as 'Boilermate' has
been around for a long time. It has however evolved during this time
and if you are replacing an elderly unit (or for that matter
planning to incorporate one in a new installation) you should be
aware if fundamental differences between old and new models.
What is a Boilermate?
The answer to this rather depends on
the age of the unit you are trying to describe as the function and
appearance has somewhat altered over the years.
Pictured right you
will see a Boilermate A Class OV - very different in appearance to a
Boilermate II for example, or the newer Boilermate BP shown below.
Essentially, the Boilermate is a
Thermal Storage Unit. A thermal store, as the name suggests, is
something that stores thermal energy. Thermal stores, as they are
generically known, are available from different manufacturers and
typically store their energy in a mass of water contained within the
unit which is open vented - this is to say the water stored is at
atmospheric pressure, not sealed, pressurised or 'unvented'. Rather like a
massive bucket. Gledhill (the manufacturer of Boilermate) took the
principle of an open vented thermal store (a concept favoured for
it's safety when compared to unvented systems) and incorporated
several functions into their unit and gave it a snazzy name.
As mentioned, the Boilermate unit has
changed both in appearance and function due to product development
(and other factors) over the years. The earlier models looked like a
cylinder with various pipework, whereas the newer versions resembled
a rather unassuming office cabinet with concealed pipework.
What function does a Thermal Store
The core function of a thermal store
is to collect and store energy. Hence, a Boilermate is an energy
store. But, the Boilermate (depending on model) utilises the stored
energy to perform other domestic services. The most desirable
function of a thermal store (and therefore a Boilermate) is to
provide provide mains pressure hot water whilst remaining safely open
vented. A contradiction you might
think (mains pressure hot water from an open vented store?) but this
is the somewhat clever part - heat contained within the store is
simply imparted to mains pressure cold water passing through the
unit. The method by which this operation is achieved marks the
difference between products offered by manufacturers and indeed the
different models within the Boilermate range.
What function does a Boilermate
Gledhill exploit the desirable characteristics
of open vented thermal storage, package it with other useful functions and sell it as an 'all-in-one' branded
product - The Boilermate.
The Boilermate developed
into a hot water management system that took care of both heating
and hot water requirements for domestic properties. Designed to work
in conjunction with a boiler (hence the name 'Boilermate')
the product soon became popular with major housing developers not
only for it's performance but also for it's ease of installation -
wheel it in, put it down, connect it up. Delightfully simple for the
plumber, a full water management system in a single product - and no
fiddly items of valuable stock for the developer to leave on site
and keep an eye on!
The Boilermate evolved from a
cylindrical thermal store with a host of visible pipes and external
components into a neat cabinet containing everything the unit needed
to perform it's function concealed behind a removable front panel.
Mains pressure hot water, a fully open
vented store (a great safety feature), central heating control,
boiler control, all the pumps and gadgets needed to manage household
requirements were incorporated into the Boilermate. As the product
continued to develop (Boilermate 2000 and later) the unit saw the
introduction of an optional 9kW electric boiler that could be used
in emergencies if the main boiler were to breakdown. This feature
became a standard fitment on the Boilermate 'A Class'. Little by
little the unit became more and more 'clever'.
How do you get mains pressure hot
water from an open vented thermal store?
The principle is simple, although
achieving it is somewhat more complex. This contradictory scenario
is achieved through heat exchange. Heat exchangers are utilised to
take pre-heated water from the thermal store (which is open vented)
and impart the energy into the mains pressure water passing through
the unit. It's as simple as that. All of the dangers (risks of
explosion) associated with unvented cylinders simply disappear
because an open vented store cannot explode. So you get all the
benefits of mains pressure hot water with none of the risks.
Reliability of the Boilermate
The Boilermate continues to be a good idea. To
exploit elements that safely deliver mains pressure hot water
without any of the dangers must be a good thing, but Boilermate hit
a bit of a problem - it became complex.
Boilermate had developed into an entity that required a brain. Although heat exchange
technology is simple to achieve, stabilising output temperature
opened up a whole new can of worms. In order to utilise a plate heat
exchanger with a high flow potential AND achieve a stable output
temperature the speed at which water from the store was pushed
through the exchanger had to be regulated. This meant modulating
pump speed to vary heat exchange in response to strategically placed
temperature sensors monitoring input and output temperature. Control required a
microprocessor which of course gave rise to the need for electronics
and circuit boards. Electronics took over the control of all system
functions. Unfortunately these complexities have proved to be
expensive things to fix when they go wrong and of course like
anything complicated it will go wrong.
Getting a Boilermate fixed
Getting somebody to work on a
Boilermate has been an issue for many people over the years. Mention
a thermal store to your average plumber and he'll look at you as if
you were speaking ancient Hebrew. Mention Boilermate and you're lucky
if they bother to close the door behind them as they run away. To
most plumbers Boilermate is rocket science and there's never a
scientist around when you need one!
In reality the function and principle
of Boilermate is not all that complicated, it just needs a willing
and open mind. Principles of thermal storage are in themselves
fairly easy to grasp, but many plumbers either can't be bothered or
become petrified at the thought of learning something new. Surround
a thing with electronics that was already off-putting and you won't
get a warm reception. For this reason owners of Boilermates around
the country are happy as can be while they work, it's when they go
wrong it becomes apparent that help is in short supply.
In short, models of Boilermate up to
and including the 'Boilermate A Class' were good at what they were
designed to do so long as they didn't go wrong. When they did (and
continue to do so) it can be difficult to find a person who will
understand and tackle a repair and spares can be a little pricey.
The new generation of Boilermate
Towards the end of the 2000 decade the
Water Storage division of Gledhill that manufactured the Boilermate
went into liquidation. It's reliance on the 'new build' housing
market proved to be the downfall. Boilermate as we knew it ceased to
However.... Gledhill is made up of
several divisions, so manufacture of the Boilermate range (along
with others) transferred to the Building Products division. From
then Boilermate would carry a 'BP' suffix.
The Boilermate BP
When the Boilermate product was
transferred to the Building Products division of Gledhill it
underwent quite a major change. Taking a positive view of the
changes one might argue that the product was improved by removing
all the complicated technology required to run to older model. But
how you might wonder?
As mentioned earlier, the Boilermate
had become complicated and required microprocessor control for time
functions, pump speed modulation, switching etc etc. By utilising a
different type of heat exchange mechanism (an immersed heat
exchanger) the new BP model no longer requires pump control.
Furthermore, where the older model controlled DHW output
temperature by varying the heat exchange process (by modulating pump
speed) the new model simply uses a TMV (thermostatic mixing valve)
on the outlet to limit the temperature that hot water can be
delivered to taps. Genius you might think, but not really. Yes it is
great that a simpler way to achieve mains pressure hot water had
evolved, but it came at a price.
How does the Boilermate BP differ
The concept of Boilermate was (in the
early days) a total water management system. A system that could
deliver mains pressure hot water while remaining open vented itself.
A great idea doing away with the dangers of unvented cylinders while
retaining the performance. You simply needed to feed the unit with
heat from a boiler and the unit would handle all domestic hot water
(DHW) and central heating requirements. Furthermore, the DHW output
flow potential was huge - up to 35 litres per minute. In reality
very few domestic properties have the ability to procure 35 litres
of water per minute, but the potential was within the capability of
the Boilermate. The new Boilermate BP does not and cannot do the
There are several obvious differences:
Boilermate BP unit picture right - front cover removed)
Firstly, the new BP model does not
contain any sort of control function. This is to say there are no
programmers, switches or microprocessors in the unit. Any control
function required must be provided externally.
Secondly, the Boilermate BP does not
output to central heating. Whereas the older unit would send
pre-heated water off to the radiators on demand the new one doesn't. There is
no central heating function to the BP model.
Thirdly, the only function of the
Boilermate BP is to provide mains pressure hot water while
maintaining an open vented thermal store. That's it. The unit now
installs to a heating system in the more traditional 'S' or 'Y' plan
Is the Boilermate BP suitable as a
replacement for an older type?
In a word, Yes. But, you will have to
bear in mind all that has been explained in the section. An older
type Boilermate as you know managed central heating needs. The BP
If you compare the
two pictures above you will see how very different the older
A Class (top image) and lower BP model (black &
white image) are.
Remember, the Boilermate BP is now a
device that creates mains
pressure hot water ONLY. You will need to make fairly minor
alterations to existing pipework in the vicinity of the old unit,
add an external programmer, zone valve/s and possibly a circulating pump in order
to replace an old Boilermate with a new one. On a
more technical level there are one or two other differences.
Firstly, earlier models of Boilermate
did not have a heat exchanger (boiler coil) on the input from the
boiler. Boiler water was circulated straight into the shell of the
cylinder. Sister product to the Boilermate was the 'SystemMate'.
This was a Boilermate with a boiler coil allowing a
pressurised radiator circuit. The BMBP comes with a boiler coil as
standard which is now the only way heat may be imparted to
the unit. This of course
means that the unit can be used on a sealed radiator (pressurised)
system or a fully open vented system. Having a boiler coil means the
BP model can also be used as a replacement for a System Mate
(bearing in mind all the modifications/limitations mentioned that
shall apply). There are no options available, the BMBP is a 'one
type suits all' product and the unit will only accept one heat
Secondly, the hot water delivery rate
on the BP is slower than the old models were able to manage. Instead
of a colossal 35 litres per minute the new model delivers up to 18
litres per minute on the 125, 145 and 185 versions and up to 22
litres per minute on the 215 and 225 models.
Is the Boilermate BP as good as it's
This really is a matter of opinion.
Better, one might argue, if you consider the removal of components
such as microprocessor circuit boards, pumps and a plate heat
exchanger a good thing. After all, the more simple something is the
less likely it is to break down. But then, is the Boilermate BP
really a Boilermate at all? Boilermate used to refer to a clever box
of tricks that would manage heating and deliver oodles of mains
pressure hot water whilst maintaining an open vented thermal store.
The new BP model delivers the hot water (albeit less of it) but
does nothing else as it doesn't have anything to do with the heating. So in effect the
Boilermate BP is now just a thermal store in a cabinet.
Alternatives to Boilermate
Now that Boilermate is simply a
thermal store in a box, and because we know you will need to
modify existing pipework during the process of replacement, you are of course
no longer 'tied' as it were to the product. Replacement (if you wish
to stay with the technology) will involve you buying a new thermal
store (this is all a Boilermate is now) so you are at liberty to shop about.
In an attempt to keep things simple we
will assume you wish to continue enjoying the benefits of mains
pressure hot water together with the safety of an open vented
thermal store. So which way should you go?
Top of the list must of course be to
install a new type Boilermate BP. Perfectly understandable if you
desire the cabinet style of the Boilermate BP. Just be sure you
understand the differences between the new and old models and the
alterations to plumbing and controls you will need to undertake. And remember, Boilermate BP is
just a thermal store in a box. Nothing more.
If you are less concerned about 'the
box' in which the Boilermate houses its store then you might like to
look at a cylinder type thermal store.
There can be numerous advantages in
considering a proper cylinder shaped thermal store. Not least is the
fact that you can run heating directly from a cylinder type store
should you wish in much the same way as the old Boilermate models
used to. In short, cylinder type thermal stores are more versatile.
Depending on the model you choose, cylinder type thermal stores will
accept multiple heat sources simultaneously, provide mains pressure
hot water AND remain open vented. They are therefore much more
versatile than the Boilermate BP.
Which cylinder type thermal store
should I choose?
Firstly you should take a look at the
various options available to you. Gledhill (the manufacturer of
Boilermate) make their own cylinder type thermal store called the
Torrent Mulitfuel Store. Gledhill, in keeping with the company's
propensity to brand their products with catchy names, have
christened their thermal store cylinder with a name that describes
the cylinder's function quite well. It is however only a thermal
store and arguably does nothing more than other similar products.
You might also like to look at an
alternative range of thermal stores that are available (follow
the link for full info). These cylinder type thermal stores haven't been given
snazzy names they simply perform the same
You might be interested to know that
the Gledhill Torrent Multifuel store is available ONLY as described.
The alternative cylinder however can be adapted and/or modified to
customer specification and is available in cylinder and combination
Thermal store cylinders can generally accept heat input
from various sources such as solar, wood burners, AGA's, oil and gas
boilers, air recovery and ground source heat pumps. The process is
simultaneous, they remain open vented and all provide mains pressure
A thermal store is in some ways unique
as it possesses the ability to accept heat from sources that are
deemed 'uncontrollable' such as wood burners and AGA's. The
inherently open vented nature of a store makes this possible without
the risk of explosion.
Check them all out before you decide
as there is often a price differential that cannot be ignored. You are
always welcome to call our office for advice if the going gets a
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Boilermate BP section