How can anyone describe the work involved!
Each installation is unique.
Because each installation will have work to do, and possible jobs can be listed. If someone has an existing gas boiler with radiators, there will be some essential jobs, and some optional. Perhaps 15 mm radiator piping is not enough, or maybe it is. Maybe pipes in screed are not good, maybe they are. Maybe new radiators are needed. I have an online (rough) quote which assumes one extra radiator. Obviously replacing radiators e.g. single to double panel, will add cost. And adding radiators adds cost. Obviously if there is no hot water cylinder, one must be installed, and that adds cost. But that quote made assumptions about the work involved, and currently I don’t have a clue what they are.
I’ve looked for online descriptions, and they are vague marketing speak e.g. the system is optimised to the customers’s requirements with appropriate changes made to their current heating installation. Thank goodness, I had assumed it was just bodged together according to the contractor’s mood on the day.
With gas boilers it is much easier to put in almost any unit and range rate it down to match the heat loss of the property. (or not, in most cases).
With heat pumps, an accurate heat lost calculation needs to be carried out, then a system designed so that the Mass flow rate will suit the demands and expectations.
Okay, so we have a heat loss survey and calculation to carry out. There is one (uncosted) task.
Oversizing a heat pump will not return the COP or SCOP that is the sole purpose of installing such a system (above comfort).
Besides all of this, it is not for you to adjuticate the work, and therefore costs, involved.
So the children, sorry customers, must accept whatever daddy, sorry the contractor, says.
That is a matter for the tendering businesses and you are in no way forced to accept their estimate/quote.
But if you have several quotes around the same price then you know what the current market commands...
For sure, the customer can find out the market prices, but they will not know if the prices are reasonable given the amount of work involved. If there are more customers than contractors available, then the basic rules of supply and demand apply, and the contractors will be making hay while the sun shines. I’m becoming convinced that this is a hay making scenario.
And then comes the caveat emptor of going with a firm who's quote is considerably less than the others.
The client who doesn’t have a clue what the work involves cannot decide if a quote is excessive or unduly cheap. That said, I do agree that if a quote is considerably less, it is best binned, or another quote obtained. However, the proper Heat Geek quote will cost me £250. I don’t fancy getting three such quotes, only to discover that my house would cost £20,000 with major disruption to ‘upgrade’.
When I bought my house, I got screwed over by a trade, even though I got multiple quotes. It cost me several thousand pounds. Now I educate myself beforehand.