adding a 2nd boiler or upgrade to a higher output

[the_d_o_t]

Hi,
i have been to look at a job where the current combi boiler is to small for the system it is on, i have calculated it requires 5kw more and have suggested upgrading from the old worcester 32kw to a new vailliant 37kw.
the customer has asked can we just install a small boiler just to cope with the extra rads and link it together with the existing boiler.

i have told them this is not a economical option as the old worcester may not have long left in it anyway, but they still want to talk further about adding a 2nd boiler,

what other reasons would you advise to upgrade rather than adding a 2nd

Thanks Nick

 

[Roger Welton]

Space, increased service / maint costs, increased system complexity and additional controls needed.

 

[doitmyself]

Which Worcester 32kW boiler? I assume you mean the Vaillant 837 combi, which only produces 28.6kW for heating.

How did you calculate the 5kW extra required?

Does the customer realize that you can't buy a 5kW boiler?

 

[Ermintrude]

Put in logic 24kw system boiler then a logic 35 combo. Sounds like a big premises for a combi me old fruity?

 

[oz-plumber]

Seems like a big effort to counteract being 5 kW short on heatload.

I'm sure there are easier solutions with the existing boiler to accommodate the 5 kW shortfall.
Have you tried balancing the system, are there TRV's installed, is the system full of sludge.?

If it were me I would try and make the existing system more efficient than going too the expense of putting in a second boiler that may not resolve the issues.

 

[lame plumber]

a 32kw combi is big anyhow, and the high kw is only to provide a decent hw flow rate and a lot less is required to heat the house normally. I'd be interested in how many rooms your heating and how many bathrooms there are before making any further comments on if another boiler is needed, as if the place is that big, it shouldnt be running of a combi in the first place. My own home has a combi running some 16 rads and only one bathroom for hw water the other shower room using an electric shower, so the place you are looking at must be massive as my combi is a 28kw model.

 

[sheff paul]

Hi,
i have been to look at a job where the current combi boiler is to small for the system it is on, i have calculated it requires 5kw more and have suggested upgrading from the old worcester 32kw to a new vailliant 37kw.
the customer has asked can we just install a small boiler just to cope with the extra rads and link it together with the existing boiler.

i have told them this is not a economical option as the old worcester may not have long left in it anyway, but they still want to talk further about adding a 2nd boiler,

what other reasons would you advise to upgrade rather than adding a 2nd

Thanks Nick

Don't dick around fitting additional boilers,upgrade the pipe work to 28mm off the boiler if it isn't already,pipe most of the rad circuit in 22mm,this will help it,when the existing boiler packs up you have a better system to fit a new boiler to it.Power flush if needed and fit a filter.

 

[smhstu]

Or change for a CDI classic 35kw system boiler and unvented cylinder

 

[Ermintrude]

Or change for a CDI classic 35kw system boiler and unvented cylinder

Cdi regular much better and last longer 42kw