When Guidance Becomes Noise — and Why Engineers Need Clarity

Helping YOU find good heating engineers. We share case studies from engineers in the Guild of Master Heat Engineers to help people find top installers, help gas and oil engineers increase their knowledge around heat pumps, and provide a solution for third-sector professionals to understand the industry better.

Overview

This commentary examines:

• why good engineers are increasingly confronted with conflicting interpretations of Building Regulations,

• how trade bodies and manufacturers sometimes misrepresent guidance as fixed regulatory requirements,

• and why accurate understanding of the Building Regulations matters for safe, compliant, and forward-thinking engineering practice.

When Misinformation Becomes a Systemic Problem

Engineers today operate in a crowded, noisy landscape. The UK has one of the most competitive markets in the world for heating appliances and components. Almost every manufacturer has a message; almost every trade association has a stance. This creates an environment where even well-intentioned engineers are routinely bombarded with partial interpretations, commercial framing, or industry-shaped emphasis.

And in that noise, it’s increasingly difficult to identify what is genuinely required by law, what is supported by guidance, and what is simply preferred by a particular commercial group.

A recent memo from the Hot Water Association (HWA) illustrates this problem starkly.

What the HWA Told Its Members

“The Importance of Compliance With Building Regulation G3

The HWA technical group has been discussing a worrying trend where some heat pump, cylinder manufacturers and installers are taking the unilateral decision to remove the spring return zone valves from unvented systems connected to heat pumps. These safety valves are required to be fitted on any unvented indirect water heating system, irrespective of the heat source, and this includes heat pumps. The argument is that heat pumps can never achieve the sort of temperatures that would trigger the high limit stat so therefore it and the spring return valve are redundant. But G3 is not a pick and mix, you do not get to choose which part of the regulations you will comply with and which parts you will ignore.

Members should be aware that removing the zone valve means that the system is non-compliant according to G3, negates any NSF, WRAS or Kiwa approval and opens them up to significant potential liability if something should go wrong.

In order to address this issue and to reiterate the importance of complying with all of the regulations around safety controls on unvented equipment, the TG has produced a G3 controls document that all of the members should read, understand and advise customers accordingly.

Any questions, please do not hesitate to get in touch.”

The problem with this memo is not that safety on unvented systems is unimportant. Far from it. The problem is the memo misunderstands the actual regulatory framework it is invoking.

And this is not a small misunderstanding. It goes to the heart of how Building Regulations work.

A Short Personal Context

My interest in unvented systems began early. I grew up around manufacturers in the boiler and burner industry, where technical memos and engineering notes were part of daily life, including detailed documents such as this eight-page technical memo issued to boiler manufacturers’ technical representatives in 1991. That early exposure meant technical information wasn’t abstract; it was part of everyday conversation.

When unvented systems were permitted in the UK following the reforms enabled by the 1984 Building Act, I began my apprenticeship (in 1987) at Norwich, a city that happened to be home to Heatrae Sadia, one of the leading pioneers of unvented hot-water technology. Because of that local connection, my college had some of the best unvented training bays in the country.

Later, while teaching in colleges, I taught G3 and repeatedly saw how often people misunderstood what the regulations actually require, and how much confusion is caused by conflating requirements with guidance.

What Building Regulations Actually Are, & Are Not

It is worth restating something fundamental:

Building Regulations contain requirements.

Approved Documents contain guidance on how to meet those requirements.

Approved Documents use “should”, not “must” or “shall” because:

• they describe ways to meet the requirement,

• not the only ways, and

• the law must allow for innovation.

If legislation dictated specific products — e.g., “chemical inhibitors must be used”, “TRVs must be fitted”, “tundishes must be installed” — the industry would freeze. No new solution could ever enter the market without rewriting the law itself.

That is precisely why the legislation sits at the level of outcomes — e.g., “the stored water must not exceed 100°C” — and not at the level of components.

Why the HWA Memo Is Incorrect

The HWA memo asserts that removing a spring return zone valve makes a system non compliant under G3.

However, G3 does not mandate specific components.

• It mandates outcomes, including the prevention of stored water exceeding 100 degrees, visible and safe discharge from safety devices, and adequate safety controls.

• A spring return zone valve is one method of achieving these outcomes. It is not a required component of the legislation.

• This distinction matters because misunderstanding it leads to misinformation being presented as mandatory instruction.

The Wider Pattern, Trade Bodies and Mandatory Language

This is not the first time an industry group has overstated its interpretation of regulations.

Examples include:

• When BS 7593 was referenced in Part L guidance, some chemical inhibitor companies marketed inhibitors as mandatory, which they were not.

• Some individuals within the controls manufacturing community claim that frequent boiler cycling is not detrimental, despite decades of engineering knowledge.

• Some Certification Bodies auditing MCS work treat tundishes as mandatory, even though the requirement is simply for visible and safe discharge as well as the water regulations requiring prevention of backflow.

These incidents reflect a systemic issue. There are numerous associations and certification schemes, each with its own perspective and commercial context. While many people are well intentioned, the combined output can create confusion rather than clarity.

The Physics Does Not Change, On and Off Cycling and Thermal Stress

It has recently been claimed in some industry messaging that boilers cycling on and off frequently, sometimes hundreds of times a day, is not detrimental.

Engineering evidence says the opposite.

Frequent temperature swings create thermal expansion and contraction. This causes:

• cyclic stress,

• material fatigue,

• micro cracking,

• and shortened service life.

These are well understood physical effects, not disputed opinions.

The Certification Body Problem

A concerning example is the misunderstanding of G3 among some Certification Bodies. One CB auditing AIRA’s heat pump installations believed that a tundish was a mandatory requirement.

It is not.

The requirement is that stored water must not exceed 100 degrees, and that discharge must be visible and terminate safely.

A tundish is one recognised method, but not the only one.

When auditors misunderstand regulations, engineers face contradictory expectations and inconsistent inspections. With around nine separate CBs auditing MCS heat pump installations, the potential for inconsistency is significant.

A Transition of Power, Why This Is Happening Now

A useful idea from communication research is the concept known as the Transition of Power.

Before social media, companies controlled the public message through one way communication. They could frame their products however they wished, with little challenge.

That model has disappeared.

Engineers now have platforms. They can challenge claims publicly. They can ask for evidence. They can point out errors.

Manufacturers and trade bodies increasingly have to listen.

The recent HWA memo prompted exactly this kind of response. Engineers raised concerns publicly, and the Heat Pump Association, via Damon Blakemore, listened and I have heard will be responding soon. This is a positive development.

Why Clarity Matters

This is not really a debate about valves. It is about something more important.

Engineers need clarity,

the industry needs accuracy,
and Building Regulations must be understood as they are, not as people imagine them to be.

Good engineers will always meet the legal requirements and strive for safe, robust installations. They should not have to navigate conflicting memos or commercially shaped interpretations to do that.

The UK is full of highly capable engineers. What they need is clear, correct information, not noise.

Closing Reflection

The heating industry is changing rapidly. Heat pumps, modern controls, new materials and new system philosophies are reshaping everyday practice. In times of change, misinformation spreads quickly, especially when many associations all speak at once.

Our role as engineers is to return to the fundamentals, the actual legal requirements, sound engineering principles, and shared professional judgement.

If industry bodies commit to accuracy, and if engineers continue to engage constructively, the sector will improve.

Clarity is a safety issue, and good engineers deserve nothing less.

The Guild of Master Heat Engineers is supported by our Patrons.

Learn more about our Patrons here.

Have a great week everyone.

Nathan

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