Boiler Options

1. Grandee Combi Condensing.

These appliances produce central heating and domestic hot
water (at mains pressure). No tanks in the loft are necessary
whether for the heating or the hot water circuits.

Key Features:

• High efficiency
• Mains pressure potable water
• Smaller, faster and simpler to install and service

2. Grandee System Condensing.

These are similar to standard condensing models but
incorporate the principle components of a sealed system. No
feed and expansion tank in the loft is needed.

Key Features:

• High efficiency
• Smaller, faster and simpler to install and service

3. Grandee Standard Condensing.

These boilers are suitable for central heating and production
of hot water through a hot water system such as a hot water
cylinder and system filled by a feed and expansion and water
storage tanks in the loft.

Key Features:

• High efficiency
• Volume stored hot water

4. Grandee ECO POD Condensing

5. Grandee External Condensing

Flow Rate - an explanation.

How is Hot Water Produced?
Either Directly from the heat source as with a gas or electric water heater or shower or indirectly by
heating primary water within a boiler which is then used to heat secondary domestic water as in a
copper cylinder or via a plate heat exchanger.

The mathematics
A kW (Btu/h) is the amount of heat needed to raise .45 litres (1lb) of water by .55°c (1°F). Therefore a 17.6kW/h (60,000 Btu/h) output boiler, in ideal conditions can only raise 4.5 litres (1 gallon) of water a minute by 38°C (100°F) which, in our opinion, is neither hot enough or sufficient for most people. In order to increase the temperature and volume of hot water it is necessary to either increase the boiler output substantially (and risk excessive cycling in the heat mode) or provide a thermal store or ‘battery’. A sensible compromise may produce the most satisfactory results.

The spurious claims
One leading manufacturer claims “…15 litres (3.3 gallons) per minute at 37°C…” which is almost body temperature. We consider this inadequate and that hot water needs to be about 50°C. Others claim “…6 to 24 litres/min…” dependant on the water pressure or other circumstances - a variance of 400%! An elastic claim, too far stretched? Some oil combis provide such a large thermal store that the time to heat and recover is probably too excessive.

So What is the Answer?
In our opinion, to design a boiler whose output is matched to the heating load with an integrated thermal store sufficient to enable generous flow of hot water. In other words, sufficient for a hot bath and with rapid recovery.


The Options

1. Boiler and Copper cylinder - Primary water is heated efficiently, but the tank of water can take up to an hour to heat. The water then stratifies.

2. Boiler with no thermal store - Efficient at producing hot water but unless the output is substantial the amount of hot water is limited.

3. Boiler with separate thermal store - Primary water production is efficient, but as with a copper cylinder, secondary domestic water is slow to heat.

4. Grandee Boiler with integral thermal store - An efficient method of producing primary heat - no secondary tanks. The boiler is sized to the heating load and thermal store pro-rata. MUCH MORE EFFICIENT than methods 1 and 3 and produces more hot water than method 2.

Conclusion - We claim that Grandee Combi, output for output, produces hot water better than any other oil combi known to us - or your money back