TWO PUMPS

[Paul Barker]

These days I switch off about the nursing, if I saw someone I could help and nobody proficient had intervened I would help but haven't needed to yet.

A bit of water cascading down someones stairs in the middle of the night might make them speak falsetto but it's very minor stress to me after nights in charge of a children's ward in a general hospital.

 

[desbarron]

Paul
Tell me about it.
Currently use a Laars Natural Gas about ten years old. Runs well replaced a great expense the heat exchanger last year. I now watch the PH levels more carefully!

 

[doitall]

What size pump have you got, ans is it on the flow or the return.

Does the index radiator get hot.

And what size is the main pipe runs.

What type of system is it, sealed or open vent.

Boiler, make and model.

 

[desbarron]

Problem resolved thanks to Paul

 

[desbarron]

New pump installed system works a treat.
Many thanks
Des

 

[Agile]

And you questioned Paul's credentials?

If he was helping you when you were having a heart attack then I dont think you would bother to question him then!

Its unusual to find a Laars boiler in the UK when its not for heating a swiming pool.

Failure of a Laars boiler heat exchanger is usually caused by a lack of water flow!

Looking at the posting history, it would really be DIA who pointed you in the direction of the pump!

Tony

 

[desbarron]

You should read more.
No reason not to ask for his credentials.
It was not DIA who suggested the second pump it was me in the original help request.
If you had read all ehe posts you would note that Paul was offering to sell me a new type of heater for my swimming pool. Which is where the laars is used. With swimming pool its high PH which eats through exchangers.

 

[doitall]

You should read more.
No reason not to ask for his credentials.
It was not DIA who suggested the second pump it was me in the original help request.
If you had read all ehe posts you would note that Paul was offering to sell me a new type of heater for my swimming pool. Which is where the laars is used. With swimming pool its high PH which eats through exchangers.

No is wasn't me

Fitting a second pump is only getting over a problem with the design/installation.

As I asked, if the index radiator gets hot they all will.

but what the hell it works so every ones happy.

As for the swimming pool fit a stainless steel heat exchanger, designed for pools, the boiler can be converted to indirect then.

 

[desbarron]

Your right system should have been designed with two pumps from day 1.
With correct Ph the heat exchanger will last twenty years so why change it.
Thanks for your help.
des

 

[Agile]

Only if you do that be aware as they all seem to be from the US their heat transfer rating is based on a flow of 80 degrees C from the boiler which does not make for use at that rating witrh a condensing boiler.

Rate at 50% of the plate with a boiler flow of 60 C and they will give very efficient heating.

Only trouble is people will spend £30 k on a pool and will not spend and extra £600 for a condensing boiler which would repay twice that in the first season.

I would still repeat that all the Laars boilers that I have seen on direct water heating have failed as a result of scaling of the tubes. This causes them to overheat and start leaking, usually at the tube ends.

Tony

 

[desbarron]

I have had laars for over 20 years running 366 days a year with the pool water at 90 degrees with no problems until last year. I had it checked and the diagnosis came back that the ph level was too high I checked the pool ph something I never do and it was sky high. The new exchanger came from the US and had a large warning about keeping the Ph high. Incidently there was no scalinmg on the exchanger that failed so it probably depends on the water quality in the area.
I will take the connecting pipes off and check for scale just in case with the correct ph the pipes start to scale.

 

[Agile]

Its not necessary to open it.

Start measuring temperature in celcius instead of Fareinheight and then measure the flow and return temperatures using a contact thermometer.

As long as they are both well below 50 C there should be little scaling problem. The temperatures depend on the water flow rate.

Perhaps yours was attacked by the chemicals you use to treat the water but it is quite important the check the water and correctly dose it accordingly.

Tony

 

[doitall]

Your right system should have been designed with two pumps from day 1.
With correct Ph the heat exchanger will last twenty years so why change it.
Thanks for your help.
des

Disagree completely.

You only need one pump unless the system has been zoned, then you would have a pump and controls for each zone.

Just to avoid my confusion, is the same boiler doing the heating and swimming pool.

 

[Agile]

Thats an interesting question John.

I had assumed that although the posting had referred to the Laars it was as an aside and the Lars was stand alone and directly heating the pool water. However we have not been told what the house boiler is !

If the Laars boiler is directly heating the pool water as implied by saying the boiler HE had failed due to pool pH then that means the pool water would be circulating through the rads if there was only one boiler! That would NOT be a very good idea!

I have only once come across a house boiler being used for pool duty and I have never seen a condensing pool boiler even though the savings would pay for the boiler in the first year in many cases.

Tony

 

[desbarron]

Glad you think it was a good question, I thought it idiotic. Not to mention such a crass arrangemet at the start would have been inane. Did he really think the pool water was circulating through the boilers in the house or if indirect I would not have mentiooned it when I described the system. Too many contributors dont bother to read the whole thread.