boilers in tandem.

[Durgo]

This is why I resent paying taxes - as Ive said elsewhere, they use my own money against me these asylum seekers are probs also jobseekers on scratching on day and doing cheapa nd dodgy plumbing the rest of the time

 

[Onetap]

Hi there, quoting for a job in a house converted into 12 flats.
At present the boiler is an ideal istor,i think its 30 kw with about 100 litres of stored hot water from unvented cylinder.
I was thinking of fitting 2 baxi solo 30kw boilers running 2 megaflo 250 ltr unvented cylinders and 20 rads totalling 17 kw in total.
There are 12 mixer showers,hand basins and sinks to supply.
Not had much feedback from any suppliers,i work for a social housing firm and they had a quote for a commercial system for 8k , but they were only fitting a 40kw boiler and havent been forthcoming wuth a written quote !!
I have got this priced at 4k for the firm, any advice would be appreciated guys.

I would suggest;

1) Use two or more domestic-sized modulating system boilers, then your local Corgi contractor can do servicing and repairs. Ensure the boilers are suitable for use with a 0-10V control signal from an external controller.

2) TRVs in all rooms, one rad with no TRV in a communal area with an room air temperature sensor; outdoor temperature sensor on the north wall.

3) Variable speed pumps on the heating circulation to limit the system head & TRVs chattering on low load.

4) Weather compensation/outdoor reset on the heating system, reducing the heating flow temperature as the outside air temperature increases.
The heating will probably be on most of the time, limiting the flow temperature will prevent the users having sauna heat at your expense.

5) Constant speed pumps on the boiler, piped primary/secondary off the heating low loss header. The pump draws water from the LL header, and circulates it through the boiler and back into the LL header. The burner modulates to maintain the required flow temperature.

6) the controller will operate the boilers in sequence, the control signal to one boiler increases from 0 to 10V, then the signal to the second boiler increases from 0 to 10 V as the boiler demand increase from 0 to 100%.

7) DWS supplied from storage cylinder(s) if you have space. The DHWS is supplied by a secondary circuit with it's own pump, piped to/from the \LL header.

If you want a drawing you'll have to find someone who understands that and has time; and I have done it before.

 

[lagunaglen]

Thanks to all those who gave technical help, to the rest, i just go to work for my company, i cant pick and choose my customers or alter the immigration policy of our government, should i refuse to work and lose my job cos they are asylum seekers, and also scatman its not a rubbish idea, i phoned heatrea sadia for advice and after explaining my ideas they said it would work with 2,300 ltr cylinders, we have budgeted for a 3rd cylinder if the need arises