Hi all,
My Ideal Istor boiler has recently been condemned as it had somehow formed hole in the flue manifold and parts were obsolete. A shame really as although it has a bad rep it's served us well over the years with not that many issues.
Anyway, we didn't have the funds for an all in one Viessmann unit (think the 333)and didn't have the space for a separate cylinder so replaced the Ideal with a Navien 40kw combi. I knew it would be a compromise but the DHW rates of the boiler seemed promising. 16.4lpm at a 35 temp rise and 22.9lpm at a 25degree rise. More than adequate for what we need.
I've a new 25mm mains - fitted years ago mind, the Istors 22mm pipe feed now to the Navien (although reduced to a 15mm connection) and 25lpm at the outside tap and 3bar pressure (not sure if this is static or dynamic but it was a gauge screwed to the outside tap???). Gas pipe is 22mm probably 20 feet to boiler). There is a tee off at the stop tap where it enters the property leading off to the cold supplies for the house. The hot water supply pipes to a bathroom and ensuite and kitchen from boiler are 22mm (again from the old Istor) which tee off in 15mm, the cold water pipes seem to be in 15mm to the various outlets.
The boiler has been installed by approved Navien fitters but will, at best, achieve 9.5-10lpm with the hot water (there is a digital display which you can set to lpm). The fitter doesn't know why and is contacting Navien - he assures me he's seen much higher readings on 40kw Naviens. After all, they said the boiler would be ideal for my requirements.
I just wondered whether the quoted figures related to the flow rate when hot water is mixed with cold? I guess then it probably would be a much higher flow rate which is why the showers seem ok. Apparently the incoming temperature is 9 degrees, so setting the boiler hot water temp to 45degrees should give approx 16lpm...but it doesn't.
Just wondered if I was missing something as my fitter couldn't shine any light on it? I never expected it to match the Istor with multiple outlets on at the same time, but I did expect a slightly better flow rate...particularly to my bath tub which we used to fill in no time, which now takes noticeably quite a bit longer to fill.
Thanks in advance for any comments.
My Ideal Istor boiler has recently been condemned as it had somehow formed hole in the flue manifold and parts were obsolete. A shame really as although it has a bad rep it's served us well over the years with not that many issues.
Anyway, we didn't have the funds for an all in one Viessmann unit (think the 333)and didn't have the space for a separate cylinder so replaced the Ideal with a Navien 40kw combi. I knew it would be a compromise but the DHW rates of the boiler seemed promising. 16.4lpm at a 35 temp rise and 22.9lpm at a 25degree rise. More than adequate for what we need.
I've a new 25mm mains - fitted years ago mind, the Istors 22mm pipe feed now to the Navien (although reduced to a 15mm connection) and 25lpm at the outside tap and 3bar pressure (not sure if this is static or dynamic but it was a gauge screwed to the outside tap???). Gas pipe is 22mm probably 20 feet to boiler). There is a tee off at the stop tap where it enters the property leading off to the cold supplies for the house. The hot water supply pipes to a bathroom and ensuite and kitchen from boiler are 22mm (again from the old Istor) which tee off in 15mm, the cold water pipes seem to be in 15mm to the various outlets.
The boiler has been installed by approved Navien fitters but will, at best, achieve 9.5-10lpm with the hot water (there is a digital display which you can set to lpm). The fitter doesn't know why and is contacting Navien - he assures me he's seen much higher readings on 40kw Naviens. After all, they said the boiler would be ideal for my requirements.
I just wondered whether the quoted figures related to the flow rate when hot water is mixed with cold? I guess then it probably would be a much higher flow rate which is why the showers seem ok. Apparently the incoming temperature is 9 degrees, so setting the boiler hot water temp to 45degrees should give approx 16lpm...but it doesn't.
Just wondered if I was missing something as my fitter couldn't shine any light on it? I never expected it to match the Istor with multiple outlets on at the same time, but I did expect a slightly better flow rate...particularly to my bath tub which we used to fill in no time, which now takes noticeably quite a bit longer to fill.
Thanks in advance for any comments.
