Another oversized and poorly designed commercial system

in London we come across endless numbers of properties with oversized boilers and highly over engineered plant rooms where a domestic gas installation would be perfectly adequate. this building has a total heat loss of under 32 kW. and yet it is fitted with 45 kW boilers and massively oversized primary headers and low loss header. to make it worse the low loss header has been designed so that it can create a short circuit through the underfloor heating system unless the boilers are run at high temperature meaning that weather compensation or low temperature operation is not feasible and so 20% extra fuel is being consumed then is necessary. we are going to fit a pair of 32 kW v200. the beauty of these boilers is that we require no bmu or boiler sequencer as the low end output is 1.9 kW. if we run both of these boilers simultaneously the low-end output combined is lower than any commercial boiler that could be selected for this installation. another advantage with having two boilers is simplicity of control. one boiler will operate the radiators in the building while the other operates the underfloor heating. one boiler to each hot water cylinder again makes for easier control. we will reuse the low loss header but discontinue the use of a lot of the exceptionally oversized primary header. the removal of these oversized primary headers should neaten up the appearance of the plant room. the video shows an endless supply of 10 m head Magna pumps. at the end of our upgrade there will be only one of these pumps remaining for the underfloor heating circuit. we will directly connect the radiator circuit to one of the boilers and utilise the internal pump to run the whole system rather than using a 10 m head pump to supply a few radiators. in the unlikely event that we find we have insufficient residual pump head we cannot use CCT and reintroduce one of the spare pumps to overcome this. I suspect this is very unlikely to be needed.

[@waldomeyer-wentzel3583]

This is more often than not the fault/intention of the M&E specifier. The more complex the design, the higher the value of their bill. They know it's oversized but also know the client hasn't got a clue what the requirements are so they just design away and invoice accordingly. Then we come along and are told to stick the the design and just install what's been specified. Plenty of rogue traders in the supposed professional industry... Thorough video as always Andrew, thank you.

[@normanboyes4983]

Oooo that’s another interesting project. I am surprised they needed to use the boilers - the multiple pumps churning the water up should have been able to heat the place.😉

[@janeg1685]

EXACTLY THAT - 20years in contract pipefitting, I all ways saw that virtually on every job - their fee usually 5% of contract price.

[@maxsmith4820]

I see this sort of thing all the time on heat pump installs on big houses, simplify where possible!

[@CommercialGasEngineerVideos]

I've seen plant rooms in palaces and can tell you for free that this looks better. Guess they are trying to make money off the material mark up. Go on Andrew, get those robbers b4 it's too late😮

[@lukecraft1265]

Sounds like a major simplification and improvement planned. Personally I would want to retain a low loss header as planned with the viessman header but configure system to keep the 3 port mixer for ufh. Fit smaller correctly sized circs.. I would do this so I have redundancy if one boiler fails. So either boiler can provide for any demand. Ufh, rads or dhw. Interesting video, thanks for sharing.

[@andrewmillwardwatford9410]

I can't retain this low loss header if I'm going to use it to supply to circuits as it is incorrectly designed for this purpose.

[@joe90d2]

They must have shares in pump company 😂

[@CommercialGasEngineerVideos]

On a serious note, which big company on the stock markets owns or makes pumps. I'd love to know

[@dannywilkins887]

That would have been designed by a m&e consultant, they always oversize everything I’ve seen endless times

[@matthewtrueblood408]

Totally agree. Most m&e consultants just copy & paste from other tenders. Seen it so many times. But over-engineering & over-specifying also happens domestically. We see a lot of the blue van brigade quoting to putting 30kw heat only boilers when we do a full house heat loss survey that comes to about 16-18kw. Crazy

[@griffithsheating]

That’s about 2kw worth of pump power 😅

[@hiltonshaw5528]

Standard nonsense on most commercial installations