Two pumps on a heat only boiler quotation

[JackK]

I had a valiant master tech boiler installer come to me today - It was a funny experience - To keep it short his advice was:

Install a sealed system on the one pipe
Move the cylinder to the garden adjacent to the boiler

When I asked about the pressure and leaks he said "If it leaks its a good thing because it exposes a problem with your pipework" He did not understand the boiler system or what pipe was flow and return or how to cut into steel pipes

Basically a valiant master tech who had zer knowledge of anything other than system and combi on a two pipe system - AmI being fussy for expecting a lot more then just this sort of generic advice?

Thats why I turn to this forum - To cross check the information and pick out the good engineers from the useless

 

[JackK]

Just looking at it from another angle re need for LLH/PHEX etc from a thermodynamic point of view. I did these calcs below for someone or other who had a problem 7 rad, one pipe system and wanted to know the theoretical flows required to enable every 1.5kw rad to give its rated output, I can't really remember but I think he said that the boiler dT was too low and the boiler was sensing this and tripping. You can see from the (virtually impossible to achieve in practice) calcs that the dT is ~ 7C so in practice would assume that this is a lot closer??.with the rads output reducing progressively down the line. These calcs don't addup either as the total rad output is, by calc, 9.95kw but based on the total flow and dT is 14.96kw, will have another look.

Edit: Corrected now.

JackK might just feel the boiler flow/return to get a feel for the dT (if no thermal gun) and also inform if the 17 rads are all on the one pipe or are say half on one, one pipe and the remainder on another one pipe.

View attachment 325524

Thanks - I think some rads are on one pipe and others are not - Is it simple to tell? One thing I do know is the flow and return do get hot quickly so its not the case that the return delta is massively low

The low loss header wont seperate the potential dirty water in the radiators from the boiler - It just mixes flow and return so the boiler continues to warm up from what I understand - That is not hydronic plate seperation is it which is what I expected from a sort of plate exchange

Anyway i admit defeat - If anyone is in London and can deal with one pipe systems I would lovev to know their details - Wembley based