Gas heating quotes: instantaneous hot water or storage?

In a heating quote, hot water often determines the comfort your customer will experience every day. One person showers in the morning, another uses the basin at the same time, and the bath is filled at weekends. Discuss these situations before comparing equipment and your quote gains a clear benchmark. You can explain what the hot-water solution needs to do and which option you want to examine more closely together.

For your heating business, it helps to record space heating and hot water as two requirements initially. Wanting warm rooms does not describe how the household uses water. Nor does satisfactory existing heating answer the question of comfort in the future bathroom. Ask the customer to describe actual uses before discussing a supposedly suitable cylinder size or a particular appliance.

Describe existing comfort through actual situations

Start with what should be preserved. Ask where hot water is used today and what works well. One customer may want to keep their familiar shower experience; another may finally want to use two bathrooms independently. These statements create different tasks for the technical design. Record the situation in which the customer expects to notice an improvement, rather than simply writing “more comfort”.

Then ask when existing comfort falls short. Does someone have to wait, are simultaneous uses avoided, or does hot water take too long to arrive? Separate observed events from suspected causes. If the customer blames a small cylinder, that is initially their explanation. Your business investigates whether the appliance, distribution, usage or another characteristic determines the situation described.

The survey needs to cover the existing hot-water solution and its connection to the heating. Request available appliance documents and establish on site which components are actually present. A cylinder may belong to the current concept without its retention already being agreed. Equally, wanting a new heat generator does not automatically justify replacing every other component. Describe the verified installation so both quote options share the same starting point.

Explain instantaneous heating and storage clearly

Instantaneous water heating heats water when needed; a storage solution keeps heated water ready for later use. On its gas condensing technology page, Viessmann describes compact instantaneous appliances as well as versions with integrated storage. These are specific examples from one manufacturer’s range. The physical format alone therefore does not establish how the quoted appliance supplies hot water.

Explain both concepts through your customer’s usage: should an outlet be supplied directly by heating on demand, or should a planned reserve be available? Your technical specialist then explains which characteristics of the particular system matter. Have the output ratings and storage capacity explained from the documents for the actual model under consideration. A large casing, a familiar product name or the word “combi” does not replace this comparison.

Avoid ranking one approach above the other in general. Saving space may matter to one household, while another prioritises simultaneous draws. Both are valid goals. Your task is to explain the consequences of the chosen solution. By the end, the customer should be able to say which uses were considered and what limitation or additional requirement comes with the option.

Describe simultaneous uses more precisely than occupant numbers

The number of occupants is a starting point, not a complete usage profile. Ask which draws really need to happen at the same time. Two people might shower in sequence or regularly use two showers together. For the discussion, that distinction is much more useful than “two-person household”. Also record whether usage is likely to change and whether that change is already planned or merely conceivable.

A simple sketch made together can be enough: downstairs bathroom, upstairs bathroom, kitchen and the desired overlaps. Mark the combination that particularly matters to the customer. They do not need to derive technical values from it. Your specialist translates it into a verified requirement and explains whether further information about outlets or fittings is needed. This keeps the discussion clear without turning an everyday sketch into a completed design.

Distinguish regular use from an occasional peak. Filling a bath occasionally may carry different weight from two parallel showers every day. Ask what adjustment to daily routines the customer would accept and what they would not. They should not discover a restriction after installation. Nor should an infrequent event quietly become the sole basis for a larger proposed solution without a discussion of the reason.

Assess cylinder space as part of the complete quote

When considering a cylinder, discuss its location. Ask what space is actually available and how else the room is used. A supposedly empty basement area might be needed for storage or access. Have the specialist assess not only positioning but also the subsequent access required for the proposed components. The customer is choosing a solution within a room, not an isolated capacity in litres.

Include the route to the intended location. Access, doors and the existing installation can affect the scope of work. Do not ask the customer to move appliances or open components themselves. A professional survey establishes whether the option can be developed further in that location. If another arrangement is needed, describe its consequences in the quote before the customer chooses between options.

Apply the same care to a compact solution. “Needs less space” does not establish which connections and supplementary components must be considered in the actual project. Compare both options with their complete intended scope. If only one includes extra work to the room, the customer needs to recognise that difference. Otherwise they are comparing two appliance prices while choosing between two projects of different scope.

Separate waiting time from supply at the outlet

Ask separately about waiting for hot water and supply during a longer draw. The customer may describe both as “not enough hot water” while referring to different situations. Let them explain when the problem happens and what follows. This description helps your technical team choose the right investigation instead of prematurely offering a new appliance as the answer to every comfort problem.

Also discuss which outlet sets the benchmark. The nearby kitchen and a more distant bathroom may produce different experiences. Have the existing distribution and, where relevant, circulation assessed professionally. Choosing a cylinder does not automatically promise immediate hot water everywhere. The service offered must relate to the complete system that was examined.

Statements about drinking-water hygiene and operating settings require the actual technical design. Do not sell a temperature you have chosen yourself or a general operating rule as an advantage of one option. Have the responsible specialist explain which requirements are being considered for the installation and which operating instructions apply after completion. The customer benefits from a professionally suitable supply and clear instruction, rather than an unverified number on a quote.

Compare two options in an understandable case

The following example is fictional.

A household currently uses one bathroom and plans a second. The customer wants two people to shower at the same time in future. They also want enough usable space to remain in the existing utility room. Record both goals with equal weight and have the specialist establish which hot-water solutions can be examined further for the surveyed installation and planned draws. Document the second bathroom as a planned change.

For the instantaneous option, your quote describes the actual proposed appliance, the assessed usage scope and the associated work. For the storage option, add the intended cylinder and its location. Explain whether both quotes are based on the same simultaneous draws. If the assessment so far shows that one option cannot cover the desired use, do not present it beside the other as an equivalent choice.

Suppose the location assessment for the storage option is still outstanding. The next step is to assess that location before promising a complete installation scope. The customer can initially decide whether to investigate this option further. The instantaneous option is not automatically ordered merely because its description is more advanced. The conversation separates the preferred direction from the technical findings still needed.

After clarification, compare usage, occupied space and offered work with the customer. Ask them to identify the difference that matters most. They may accept a different use of the room for the preferred hot-water solution, or give more weight to keeping space free. Your advice has served its purpose when the decision fits the verified characteristics and the customer understands the consequence of their priority.

Also compare which existing components are intended to remain in each quote. If an existing cylinder could be reused, that option requires its own professional assessment of condition and integration. Do not present retention as something automatically free. Explain which assessment and connection work your business actually offers. If the existing cylinder is replaced, the agreed handling of the old appliance also belongs in the scope. The customer can then see what explains the price difference and which work forms part of each decision.

For each option, also identify which decisions still depend on the bathroom design. If the customer chooses different fittings or plans another outlet, that change goes back to the specialist. Agree which details should be settled when selecting the appliance. A preliminary drawing can be used as such, but its provisional status must remain visible during the later selection. This prevents both sides from comparing an appliance against usage that has already changed as the project develops.

Finally, ask the customer about the link between their comfort requirements and the offered scope. Can they explain what the additional cylinder is intended for, or why the assessed instantaneous option fits everyday life? If they only repeat the price difference, explain the key service differences again through the draws discussed. This question is particularly useful when several household members share the decision. It connects the comparison to actual use and provides a common basis for the next selection.

Put the hot-water choice within the heating project

Choosing the hot-water arrangement does not replace choosing the heating system. For a proposed new gas appliance in an existing German building, the currently applicable conditions for the complete project must be assessed. Sections 42 and 43 of Germany’s Building Modernisation Act concern heating replacement and requirements when installing gas-fired systems. Responsibility for this assessment belongs in quote preparation; a comfort comparison alone does not confirm installation suitability.

Summarise the outcome in a specific scope of work for the customer. It names the usage considered, the chosen option, included components and work, and any actual outstanding clarification. If the customer later changes the second bathroom plan, reassess its relationship to the previous option. Changed usage then gets a visible place in the design instead of disappearing as a passing request at the edge of the project.

Reach new heating customers with specific professional advice

On webRichtung’s gas heating page, register your business for new enquiries from Germany. Building type, existing heating and planning stage provide the starting point; heat load, floor area and consumption are not supplied. The hot-water survey recommended here is your own professional work. An enquiry is neither a finished design nor an installation order.

After registration, the welcome email takes you to webRichtung Customer. There you prepare your lead order and see the current price before placing a binding order. Bring your experience to new heating projects: register your heating business for gas heating enquiries.

Sources and technical date

Primary sources read in full on 18 October 2026: Viessmann: gas condensing appliances, GModG section 42 and GModG section 43. Manufacturer examples are not general appliance recommendations. The discussion and comparison aids are recommendations for your own advice; the responsible specialist undertakes the actual design.