Additional pump on a combi system

[Groovejet]

I Want to fit a second pump on a system, which hasd a Baxi 40he.

The house in question had been belting hot until we added 3 more rads on the third attik room.

Trying to ballance the sys. is hard work . To the point where lockshields are only being cracked open a tiny ammount to push/divert water upstairs.

If we put a pump upstairs, as the boiler is downstairs, would it be better on flow or return , or even not at all???

Will adding a pump cause confliction in the sys.
Whats the best way to go about it
Its an old detached school house and also a large house, with pipework addons here, there, everybloodywhere, so im not a fan of improving the sys. pipework.

Any ideas welcome

 

[oilhead]

Problem will be controlling the pump. If you just common it with the existing pump, then in DHW mode, you will have no feed from the diverter valve as it will be closed to the heating circuit and may cause problems. Could your problem be thatyou have insufficient boiler capacity for the system as it is now?

 

[simond]

You could power it off the room stat.

However, the fundamental prblem is going to be pipe sizing. It would better to address the cause rather than bodge an interim solution.

 

[oilhead]

powering off the room stat will still keeep the 2nd pump running when the diverter valve is in DHW mode.

 

[Groovejet]

Yea, I was thinking about conn. to the room stat.

 

[DeltaT2]

I Want to fit a second pump on a system, which hasd a Baxi 40he.

The house in question had been belting hot until we added 3 more rads on the third attik room.

Trying to ballance the sys. is hard work . To the point where lockshields are only being cracked open a tiny ammount to push/divert water upstairs.

If we put a pump upstairs, as the boiler is downstairs, would it be better on flow or return , or even not at all???

Will adding a pump cause confliction in the sys.
Whats the best way to go about it
Its an old detached school house and also a large house, with pipework addons here, there, everybloodywhere, so im not a fan of improving the sys. pipework.

Any ideas welcome

You'll not resolve your problems with a second circulation pump. The problem is clearly pipe sizing. The F&R pipes from the boiler have a limited heat-carrying capacity. You're clearly out of your depth if you don't appreciate this!!

 

[Groovejet]

You're clearly out of your depth if you don't appreciate this!

Thanks for that comment, and no im not out my depth. I thought this forum was to give advice and bounce ideas and knowledge off like minded experenced people , most of the time?
What can i do if the customer doesnt want to rip up 3 floors of pipework after they have just fitted a new 40he Baxi???
Pipe sizing is a fundemental and i just wanted to know if fitting a second pump will divert a flow to the attik space, which would of been a cheaper and less messy job.

Also thread is old news, precisely 5 month old, thanks

 

[ALEC1]

are the pipes the right size...a 24kw combi could heat 24 rads with a heat out put of 1kw each...

pipe sizing is fundafmental to heating design...

 

[Onetap]

Thanks for that comment, and no im not out my depth.

Yes, you were.

Also thread is old news, precisely 5 month old, thanks

So you didn't fix it then?

I thought this forum was to give advice and bounce ideas and knowledge off like minded experenced people , most of the time?

I started a new job around 1986. On day one the manager took me along to a job where someone had tried to rectify a persistent low flow problem between two school buildings by adding a second pump in series. Much tutting followed and he told the fitters to put in a low loss header (cross-over header or whatever you'd like to call it) although he didn't call it that; they thought he was daft and so did I.

There were no more complaints from that job, so presumably it was fixed. We never went there again and the bulky job file, from many previous visits was closed and eventually binned.

After that, I spent many evenings grappling with the dark arts of pipe and pump sizing, proportional balancing, commissioning, fixed orifice flow meters, etc, etc.. You will excuse me if I don't type the results of a few months of study on an internet post, but I really can't be bothered. You have a clue above, get yourself some books. Or pay someone for their expertise.

 

[Groovejet]

I dont understand the anamosity???
All i wanted was to chat with other engineers,
To pick peoples brains, as to speak!

My prediciment, as i said was custormer pulling me in one direction ....over mess and cost, and myself wanting to do a proper job.

I apologize if i've said anything out of line, but i thought i was asking legitimate questions???

I take pride in my work and will never leave a half finished, bodged job!

So once again Sorry, but im quite baffled with the responses ive received.

 

[gaswizzard]

No problem fitting an additional pump if pipework resitance is an issue , many combis on an S/Y plan system with additional pumps.

 

[Terry lambert]

I dont understand the anamosity???
All i wanted was to chat with other engineers,
To pick peoples brains, as to speak!

My prediciment, as i said was custormer pulling me in one direction ....over mess and cost, and myself wanting to do a proper job.

I apologize if i've said anything out of line, but i thought i was asking legitimate questions???

I take pride in my work and will never leave a half finished, bodged job!

So once again Sorry, but im quite baffled with the responses ive received.

Don't worry a out it, I cant see anything wrong with what you asked or the way you approached the forum, that's just my opinion.

If your gas safe, get yourself into the combustion Chamber.

Loads of info, and some good fellas.

 

[Groovejet]

terrydoh...thankyou 4 those kind words. Most appreciated.

Goodnite

ps- gaswizzard.thankyou for your constructive advice also . Good stuff

One thing gaswizzard could you elabarate on about fitting a aditional pump and how to link it to the leccy, and pipework 4 the best performance

No rush, going to bed now, but once again thankyou

 

[mysteryman]

It is most unfortunate that there are several guys on here who cannot or will not see that they should be helpful and pleasant - or shut up.

Don't take it to heart, they know not what they do.

 

[Agile]

Adding pumps top a combi boiler will often upset the internal flow testing.

If they must be added then on the return is usually best.

I still take the view that correcting the problem is the solution.

Balancing is virtually all done in the first turn of the lockshield.

Tony