Boiler connections......

[Itchy]

Hi....

I have got a 44kw Warmflow oil boiler to install which has 1" 1/4 flow and return connections. I thought they were going to be 28mm. Can anyone tell me if I can reduce down to 28mm soon after leaving the boiler? It is approximatley 5 metres to the DHWC and valves, on an 'S' plan.

Many thanks.

 

[Deleted member 2053]

you are looking at around 42.5 l/m of water passing throug the boiler at a 30 degree rise. This is 15-20% above the recommended flow rate for 28mm pipework.

Not familiar with your particular boiler but many new models compare input and output temperatures and will play up if the difference is too wide, which is what will happen if you can't shift enough water through it.

 

[buffy27]

Hi....

I have got a 44kw Warmflow oil boiler to install which has 1" 1/4 flow and return connections. I thought they were going to be 28mm. Can anyone tell me if I can reduce down to 28mm soon after leaving the boiler? It is approximatley 5 metres to the DHWC and valves, on an 'S' plan.

Many thanks.

throw in two bushings on the boiler itself,it is technically incorrect as the last dude said,but the reduction of a quarter inch in this situation won t make any difference...in my experience. hope this helps

 

[justlead1]

Hi, i am in Grahams camp on this one. How ever when reducing via a bush it is likely that air will be trapped in the top of boiler. If you go this route bend out of the tappings through 90degressin the vertical before reducing. Good Luck

 

[buffy27]

how would the bushings crete air lock in top of boiler.

 

[stevetheplumber]

44kw is gonna need the full bore i wouldnt reduce it down theres a lot of diffence in the flow rate between the two sizes
cross section of 28 mm pipe is 2.142x14 squared =899.2
cross section of35mm pipe is 2.142x17.5 squared=1405.12
almost double the area

 

[migoplumber]

make yourself a small header in 1 1/4 a couple of metres long, put a shunt pump between flow and return, afterthat you could reduce down if you have to.

i imagine youve quoted for the job, thats why you want to reduce. explain to your customer the complication and try to split the loss.

if the boiler comes with 1 1/4 tappings its designed for that size pipe, better to do a good install now, even if hurts a bit, than to be called out, every other day for the rest of your life because of an overheat cutout on boiler, especially in todays climate

dont put reducers straight into boiler

soz. good luck
shaun

 

[buffy27]

make yourself a small header in 1 1/4 a couple of metres long, put a shunt pump between flow and return, afterthat you could reduce down if you have to.

i imagine youve quoted for the job, thats why you want to reduce. explain to your customer the complication and try to split the loss.

if the boiler comes with 1 1/4 tappings its designed for that size pipe, better to do a good install now, even if hurts a bit, than to be called out, every other day for the rest of your life because of an overheat cutout on boiler, especially in todays climate

dont put reducers straight into boiler

soz. good luck
shaun

i have seen plenty of lads go straight to 28mm .i can see the logic in the reason not to now.fair play for the answer .i stand corrected== the header sounds a good idea.

 

[NickH]

44kw is gonna need the full bore i wouldnt reduce it down theres a lot of diffence in the flow rate between the two sizes
cross section of 28 mm pipe is 2.142x14 squared =899.2
cross section of35mm pipe is 2.142x17.5 squared=1405.12
almost double the area

Dont want to come across as pedantic but your calcs aren't quite right Steve.

Area of a circle is Pi x ( radius squared )

Pi is approx 3.142

3.142 x ( 14 x 14 ) = 615 square mm
3.142 x ( 17.5 x 17.5 ) = 962 square mm

The differance in area is still a factor of about 1.5 but your figures and calcs are wrong.

 

[Itchy]

make yourself a small header in 1 1/4 a couple of metres long, put a shunt pump between flow and return, afterthat you could reduce down if you have to.

i imagine youve quoted for the job, thats why you want to reduce. explain to your customer the complication and try to split the loss.

if the boiler comes with 1 1/4 tappings its designed for that size pipe, better to do a good install now, even if hurts a bit, than to be called out, every other day for the rest of your life because of an overheat cutout on boiler, especially in todays climate

dont put reducers straight into boiler

soz. good luck

Thanks for all the replies......

I'm both impressed and baffled by the maths!

I understand the potential for air being trapped when using a bush to reduce straight from the boiler, but both flow and return connections are on the top of the boiler so therefore would not happen.

Migolplumber, what did you mean by a shunt pump between the flow and return?

 

[migoplumber]

a shunt pump, is just an additional pump in the system, used mainly with larger boilers.

simply it is a pump connected between flow and return of your boiler, so there is always water passing through the primary boiler circuit.

when all of your system loads have been met and their circuits close, the boiler flow will be zero, residual heat in the boiler, especially cast iron jobbies will still heat the water with no place to go, after a bit the thermal cut out drops in and turns the boiler off, requiring a manual reset

a shunt pump, keeps the water moving through the circuit, and helps to prevent this, to be done perfectly the header and shunt pump would have to be calculated so they act as a "load" (rad) and can dispurse the extra heat.

good luck
shaun